P2 from Argon migration guide

Pre-release version 2022-04-08

This is an pre-release migration guide and the contents are subject to change.

P2 Rendering

The Particle P2 module is the next generation Wi-Fi module from Particle. It is footprint compatible with our prior module, the P1, but is built on an upgraded chipset, supporting advanced features such as 5 GHz Wi-Fi, a 200MHz CPU, and built-in Bluetooth BLE 5.0.

Feature P2 P1 Photon Argon
Style SMD SMD Pin Module Pin Module
Status LEDs
Reset and Mode Buttons
USB Connector Micro B Micro B
D7 Blue LED
LiPo Connector
Battery Charger
User application size 2048 KB (2 MB) 128 KB 128KB 256 KB
Flash file system1 2 MB 2 MB
MCU RTL8721DM STM32F205RGY6 STM32F205RGY6 nRF52840
Realtek Semiconductor ST Microelectronics ST Microelectronics Nordic Semiconductor
CPU Cortex M33 @ 200 MHz Cortex M3 @ 120 MHz Cortex M3 @ 120 MHz Cortex M3 @ 64 MHz
Cortex M23 @ 20 MHz
RAM2 512 KB 128KB 128 KB 256 KB
Flash3 16 MB 1 MB 1 MB 1 MB
Hardware FPU
Secure Boot
Trust Zone }
}
Wi-Fi 802.11 a/b/g/n 802.11 b/g/n 802.11 b/g/n 802.11 b/g/n
  2.4 GHz
  5 GHz
Bluetooth BLE 5.0 BLE 5.0
NFC Tag External antenna required
Antenna Shared for Wi-Fi and BLE Wi-Fi only Wi-Fi only Separate Wi-Fi and BLE antennas
Built-in PCB antenna (Wi-Fi & BLE) Built-in PCB antenna (Wi-Fi) Built-in chip antenna (Wi-Fi) Built-in chip antenna (BLE)
Required external antenna (Wi-Fi)
Optional external (Wi-Fi & BLE)4 Optional external (Wi-Fi)4 Optional external (Wi-Fi)4 Optional external (BLE)4
Peripherals USB 2.0 USB 1.1 USB 1.1 USB 1.1
Digital GPIO 22 24 18 20
Analog (ADC) 6 13 8 6
Analog (DAC) 2 2
UART 1 2 26 1
SPI 2 2 2 2
PWM 6 12 9 8
I2C 1 1 1 1
CAN 1 1
I2S 15 15 1
JTAG
SWD

† Optional but recommended. Add to your base board.

1A small amount of the flash file system is used by Device OS, most is available for user data storage using the POSIX filesystem API. This is separate from the flash memory used for Device OS, user application, and OTA transfers.

2 Total RAM; amount available to user applications is smaller.

3 Total built-in flash; amount available to user applications is smaller. The Argon also has a 4 MB external flash, a portion of which is available to user applications as a flash file system.

4 Onboard or external antenna is selectable in software.

5 The STM32 hardware supports I2S but there is no software support in Device OS or 3rd-party libraries.

6 The second UART on the Photon shares pins with the status LED, and requires unsoldering it (or its current limiting resistors) and using pads on the bottom of the module, making it impractical to use.

Hardware

Module style

The primary difference is that the Argon is a pin-based module that can be installed in solderless breadboard for prototyping, can be installed in a socket on your custom board, or soldered directly to your board.

Argon

The P2 is only available as a SMD (surface mount device) that is typically reflow soldered to your base board. Your base board will need to be a custom printed circuit board, and cannot be a solderless breadboard or perforated prototyping board.

This can be done in small quantities by hand using a reflow oven or soldering hot plate. In quantity, it would be done by your PCBA (PCB with assembly) contractor.

This is a P2 custom board, not an actual product. Full instructions on how to build this board are included in the P2 First Board Tutorial.

P2 Custom Board

The Photon 2 is a pin-based module that contains a P2, and may be appropriate in many cases. If you are planning on scaling, it may be advantageous to migrate from the Argon directly to the P2 as you may require base board changes as there are some differences between the Argon and Photon 2.

Photon 2 Rendering

Status LED

The P2 does not include a status LED on the module. We recommend adding one to your base board.

Alternatively, if you have a separate hardware control panel, it provides the ability to put the RGB LED there and not duplicate it on the module or base board.

Device OS assumes a common anode RGB LED. One common LED that meets the requirements is the Cree CLMVC-FKA-CL1D1L71BB7C3C3 which is inexpensive and easily procured. You need to add three current limiting resistors. With this LED, we typically use 1K ohm current limiting resistors. These are much larger than necessary. They make the LED less blinding but still provide sufficient current to light the LEDs. If you want maximum brightness you should use the calculated values - 33 ohm on red, and 66 ohm on green and blue.

If you are using a different LED, you should limit current to 2mA per color.

A detailed explanation of different color codes of the RGB system LED can be found here.

Reset and Mode buttons

The P2 does not include buttons on module. We highly recommend including reset and mode buttons on your base board.

For example, you could use two-inexpensive SMD switches. The 4.5mm E-Switch TL3305AF160QG costs $0.20 in single quantities.

USB Connector

The P2 does not include a USB connector on the module. We recommend including one on your base board. This can be a USB Micro B, as on the Photon and Argon, or you could use USB C.

Since you choose the connector you have the option of using a right-angle USB connector. This is handy if your board will be an enclosure where the board is recessed into the case under a removable cover. This can allow the USB connector to be accessed without removing the board from the enclosure.

Part Example Price
USB micro B connector Amphenol FCI 10118194-0001LF $0.42
CONN RCPT USB2.0 MICRO B SMD R/A Amphenol FCI 10118194-0001LF $0.42

SWD/JTAG

The P2 does not include a SWD/JTAG debugging connector on the board. We recommend including the following pins available for debugging:

The Argon has dedicated pins for SWDIO and SWCLK and SWD remains running after your user firmware starts. On the Gen 2 and the P2, the SWD pins are shared with GPIO and by default SWD is disabled once the bootloader exits.

Pin Pin Name Description Interface MCU
1 GND Ground. Be sure you connect all P1 ground pins.    
34 RST Hardware reset. Pull low to reset; can leave unconnected in normal operation.   CHIP_EN
54 D7 D7 GPIO, SWDIO SWDIO PA[27]
55 D6 D6 GPIO, SWCLK SWCLK PB[3]

If you want to include the same 2x5 1.27mm connector as is on the Argon, this is one example of the connector:

Description Example Price
CONN HEADER SMD 10POS 1.27MM Samtec FTSH-105-01-F-DV-K $3.91

Debug Connector

Troubleshooting connector

In some cases, you may want to omit the reset and mode buttons, status LED, USB connector, and SWD/JTAG pins from your board board. If you do, we highly recommend adding a debug connector to make these features available for troubleshooting. The debug connector could be an actual connector, header pins, socket, card-edge connector, or SMD pads that allow an adapter or daughter card with these features.

Voltage regulator

The P2 requires regulated 3.3VDC at 500 mA. An voltage regulator is required on your base board if powering by USB (5V), LiPo (3.7V), or an external power source.

As of the first half of 2022, supply chain constraints are affecting the availability of voltage regulator components. There is no Device OS software dependency on the voltage regulator so you can choose any model as long as it meets the voltage and current requirements.

  • This is often a switching regulator to save space, but this is not required.
    • The Photon used a Richtek RT8008 (3.3V), which is hard to procure.
    • The Argon used a Torex XCL223, which is no longer available. The pin compatible XCL224 is also no longer available.
  • If the voltage is close to 3.3V, such as 5V USB, a linear regulator can be used.

LiPo Battery and LI+ pin

The P2 does not include a LiPo battery connector or charging circuit on the module. If you want these features you will need to include them on your base board.

This is the LiPo battery connector used on the Argon:

Description Example Price
JST-PH battery connector JST B2B-PH-K-S-LF-SN $0.17

As of the first half of 2022, supply chain constraints are affecting the supply of PMICs and charge controllers. Because of this, we are not recommending a specific model to use with your board.

The Argon uses a Torex XC6208A42 LiPo charge controller, however there is no need use this part and it will be difficult to obtain.

The Boron uses a full PMIC (bq24195) and fuel gauge (MAX17043). By including these features on your base board you can provide more full-featured operation on battery power than the Argon does.

EN pin

The Argon has the EN pin which can shut down the Torex XC9258 3.3V regulator to power down the 3.3V supply to the Argon nRF52840 MCU and the ESP32 Wi-Fi coprocessor.

This feature does not exist on the P2, however you could add equivalent circuitry on your base board. This could either be a regulator with power control like the Argon, or an external load switch like the Boron (Torex XC8107). The specific load switch is not important, as long as it meets the power requirements of the MCU and any additional peripherals on 3V3.

Pins A3, A4, and DAC (A6)

Pins A3, A4, DAC/A6 do not exist on the P2 and are NC.

You will need to use different pins if you are currently using these pins. There are a large number of additional pins (S0 - S6), however.

SPI

Both the Argon and P2 have two SPI ports, however the pins are different for both SPI ports. Also note that while pins D2 - D4 are used for SPI1 on both, the actual functions (SCK, MOSI, MISO) are on different pins!

The following are all SPI-related pins on the Argon and P2:

Argon Pin Name Argon SPI P2 Pin Name P2 SPI
A5 / D14 SPI (SS) A5 / D14  
MISO / D11 SPI (MISO) A0 / D11  
MOSI / D12 SPI (MOSI) A1 / D12  
SCK / D13 SPI (SCK) A2 / D13  
A2 / D17   S2 / D17 SPI (SCK)
D2 SPI1 (SCK) D2 SPI1 (MOSI)
D3 SPI1 (MOSI) D3 SPI1 (MISO)
D4 SPI1 (MISO) D4 SPI1 (SCK)
D5   D5 SPI1 (SS)
    S0 / D15 SPI (MOSI)
    S1 / D16 SPI (MISO)
    S3 / D18 SPI (SS)

SPI - Gen 3 devices (including Argon)

SPI SPI1
Maximum rate 32 MHz 32 MHz
Default rate 16 MHz 16 MHz
Clock 64 MHz 64 MHz
  • Available clock divisors: 2, 4, 8, 16, 32, 64, 128, 256
  • Default divisor is 4

SPI - P2

SPI SPI1
Maximum rate 25 MHz 50 MHz
Hardware peripheral RTL872x SPI1 RTL872x SPI0

I2C

The P2 supports one I2C (two-wire serial interface) port on the same pins as the Argon (D0 and D1).

However on the P2, D0 is shared with A3 and D1 is shared with D4, so you cannot use A3 and A4 at the same time as I2C.

Also, the Argon supports a secondary I2C interface on D2 and D3; this is not supported on the P2.

Argon Pin Name Argon I2C P2 Pin Name P2 I2C
A3 / D16   D0 / A3 Wire (SDA)
A4 / D15   D1 / A4 Wire (SCL)
D0 Wire (SDA) D0 / A3 Wire (SDA)
D1 Wire (SCL) D1 / A4 Wire (SCL)
D2 Wire1 (SDA) D2  
D3 Wire1 (SCL) D3  

Serial (UART)

The primary UART serial (Serial1) is on the TX and RX pins on both the Argon and P2. On the Argon, hardware flow control (RTS/CTS) is available for Serial1 but this is not the case for the P2.

There is no secondary UART on the Argon, but there is one on the P2. The secondary UART Serial2 on the P2 does support hardware flow control.

If you are using Argon Serial1 with hardware flow control, you should switch to using Serial2 on the P2.

Argon Pin Name Argon Serial P2 Pin Name P2 Serial
A2 / D17   S2 / D17 Serial3 (RTS)
D2 Serial1 RTS D2 Serial2 (RTS)
D3 Serial1 CTS D3 Serial2 (CTS)
D4   D4 Serial2 (TX)
D5   D5 Serial2 (RX)
RX / D10 Serial1 RX D10 / WKP Serial3 (CTS)
    RX / D9 Serial1 (RX)
    S0 / D15 Serial3 (TX)
    S1 / D16 Serial3 (RX)
TX / D09 Serial1 TX TX / D8 Serial1 (TX)
D8 / WKP   D10 / WKP Serial3 (CTS)
Argon P2
Buffer size 64 bytes2 2048 bytes
7-bit mode
8-bit mode
1 stop bit
2 stop bits
No parity
Even parity
Odd parity
CTS/RTS flow control 1

Supported Baud Rates:

Baud Rate Argon P2
110
300
600
1200
2400
4800
9600
14400
19200
28800
38400
57600
76800
115200
128000
153600
230400
250000
460800
500000
921600
1000000
1382400
1444400
1500000
1843200
2000000
2100000
2764800
3000000
3250000
3692300
3750000
4000000
6000000

1CTS/RTS flow control only on Serial2 and Serial3. It is optional.

2On the Argon, the buffer be resized larger in Device OS 3.2.0 and later.

Analog input (ADC)

For analog to digital conversion (ADC) using analogRead(), there are fewer ADC inputs on the P2:

Argon Pin Name Argon ADC P2 Pin Name P2 ADC
A1 / D18 A1 / D12
A3 / D16 D0 / A3
A4 / D15 D1 / A4
A5 / D14 A5 / D14
D0   D0 / A3
D1   D1 / A4
MISO / D11   A0 / D11
MOSI / D12   A1 / D12
SCK / D13   A2 / D13
A2 / D17 S2 / D17  
A0 / D19 S4 / D19  

On the P2, there are no pins A3 (hardware pin 21) and A4 (hardware pin 22); these are NC (no connection). However, P2 pin D0 (hardware pin 36) can be used as an analog input and has the alias A3. The same is true for P2 pin D1 (hardware pin 35), which has the alias A4.

The setADCSampleTime() function is not supported on the P2.

PWM (Pulse-width modulation)

The pins that support PWM are different on the Argon and P2.

Argon Pin Name Argon PWM P2 Pin Name P2 PWM
A1 / D18 A1 / D12  
A3 / D16 D0 / A3
A4 / D15 D1 / A4
A5 / D14 A5 / D14
D0   D0 / A3
D1   D1 / A4
SCK / D13   A2 / D13
A2 / D17 S2 / D17  
A0 / D19 S4 / D19  
D2 D2  
D3 D3  
D4 D4  
D5 D5  
D6 D6  
D7 PWM is shared with the RGB LED, you can specify a different duty cycle but should not change the frequency. D7  
    S0 / D15
    S1 / D16
D8 / WKP D10 / WKP  

All available PWM pins on the P2 share a single timer. This means that they must all share a single frequency, but can have different duty cycles.

I2S (Sound)

The Argon can use I2S via a 3rd-party library, however there has never been support for it in Device OS.

There is no software support for I2S on the P2, and while the RTL872x hardware supports I2S, the pins that it requires are in use by other ports.

BLE (Bluetooth LE)

BLE Central Mode on the P2 and Photon 2 is only supported in Device OS 5.1.0 and later. Earlier versions only supported BLE Peripheral Mode.

Internal pull-up or pull-down

Internal (MCU) pull-up and pull-down can be enabled using the pinMode() function and INPUT_PULLUP or INPUT_PULLDOWN.

  • On the P2, the internal pull varies by pin and can be approximately 2.1K, 22K, or 42K.
    • Pins A0, A1, D2, D3, D4, D5, D10, S0, S1, S2 are 2.1K
    • Pins D0, D1, S4, S5, S6 are 22K
    • Pins A2, A5, D6, TX, RX are 42K
    • Pins S4, S5, S6 do not support pull-up or pull-down in HIBERNATE sleep mode. Use an external pull resistor if this is required.
  • On the Argon (Gen 3), the internal pull is approximately 13K.

MODE button

The P2 MODE button does not have a hardware pull-up on it, so you must add an external pull-up (2.2K to 10K) to 3V3, or connect it to 3V3 if not using a button.

Interrupts

All pins can be used for interrupts on Gen 3 devices and the P2.

There is a limit of 8 pin interrupts on the Argon; this limitation does not exist on the P2.

Boot mode pins

These pins have a special function at boot. Beware when using these pins as input as they can trigger special modes in the MCU.

Pin Pin Name Description MCU
54 D7 SWDIO. 40K pull-up at boot. Low at boot triggers MCU test mode. PA[27]
55 D6 SWCLK. 40K pull-down at boot. PB[3]
64 TX / D8 Low at boot triggers ISP flash download PA[7]

Retained memory

Retained memory, also referred to as Backup RAM or SRAM, that is preserved across device reset, is not available on the P2. This also prevents system usage of retained memory, including session resumption on reset.

On Gen 2 and Gen 3 devices, retained memory is 3068 bytes.

The flash file system can be used for data storage on the P2, however care must be taken to avoid excessive wear of the flash for frequently changing data.

Flash file system

Both the Argon and P2 have a 2 MB flash file system using the same POSIX API as Gen 3 devices. A small amount of space is reserved for system use including configuration data. Most of the space is available for user application use.

EEPROM

The EEPROM emulation API is the same across the Photon and P2.

Both the Argon and P2 have 4096 bytes of emulated EEPROM. On the P2 and Gen 3 devices, the EEPROM is actually just a file on the flash file system.

NFC Tag

The Photon 2 does not have NFC Tag support. The Argon does.

Pin functions removed

The following pins served Argon-specific uses and are NC on the P2. You should not connect anything to these pins.

  • Pins A3 and A4 on the P2 are shared with D0 and D1. You cannot use A3 and A4 at the same time as I2C (Wire) on the P2.
Pin Name Description
EN Power supply enable. Connect to GND to power down. Has internal weak (100K) pull-up.
LI+ Connected to JST PH LiPo battery connector. 3.7V in or out.
VUSB Power out (when powered by USB) 5 VDC at 1A maximum. Power in with limitations.

Pin functions added

The following pins did not exist on the Argon but are available on the P2.

Pin Pin Name Description
5 3V3_IO 3.3V power to MCU IO.
2 3V3_RF 3.3V power to RF module
31 RGBB RGB LED Blue
32 RGBG RGB LED Green
29 RGBR RGB LED Red
63 RX / D9 Serial1 RX (received data), GPIO
40 S0 / D15 S0 GPIO, PWM, SPI MOSI, Serial3 TX. (Was P1S0 on P1.)
41 S1 / D16 S1 GPIO, PWM, SPI MISO, Serial3 RX. (Was P1S1 on P1.)
44 S3 / D18 S3 GPIO. (Was P1S3 on P1.), SPI SS
48 S5 / D20 S5 GPIO. (Was P1S5 on P1.)
33 S6 / D21 S6 GPIO. (Was P1S6/TESTMODE on P1.)
62 USBDATA- USB Data-
61 USBDATA+ USB Data+
12 VBAT_MEAS Battery voltage measurement (optional).

All-purpose mapping

This mapping is good for most situations. A3 and A4 cannot be used as ADC, but I2C, SPI, and Serial are mapped.

Argon Pin Name Argon Description P2 Pin Name P2 Description P2 Pin Number MCU
A0 / D19 A0 Analog in, GPIO, PWM A0 / D11 A0 Analog in, GPIO 50 PB[1]
A1 / D18 A1 Analog in, GPIO, PWM A1 / D12 A1 Analog in, GPIO 43 PB[2]
A2 / D17 A2 Analog in, GPIO, PWM A2 / D13 A2 Analog in, PWM, GPIO 49 PB[7]
A3 / D16 A3 Analog in, GPIO, PWM S3 / D18 S3 GPIO. (Was P1S3 on P1.), SPI SS 44 PB[26]
A4 / D15 A4 Analog in, GPIO, PWM S4 / D19 S4 GPIO. (Was P1S4 on P1.) 47 PA[0]
A5 / D14 A5 Analog in, GPIO, PWM, SPI SS A5 / D14 A5 Analog in, GPIO, PWM. 23 PB[4]
D0 I2C SDA, GPIO D0 / A3 D0 GPIO, PWM, I2C SDA, A3 Analog In 36 PB[6]
D1 I2C SCL, GPIO D1 / A4 D1 GPIO, PWM, I2C SCL, A4 Analog In 35 PB[5]
D2 SPI1 SCK, Wire1 SDA, Serial1 RTS, PWM, GPIO D2 D2 GPIO, Serial2 RTS, SPI1 MOSI 45 PA[16]
D3 SPI1 MOSI, Wire1 SCL, Serial1 CTS, PWM, GPIO D3 D3 GPIO, Serial2 CTS, SPI1 MISO 51 PA[17]
D4 SPI1 MISO, PWM, GPIO D4 D4 GPIO, Serial2 TX, SPI1 SCK 52 PA[18]
D5 PWM, GPIO D5 D5 GPIO, Serial2 RX, SPI1 SS 53 PA[19]
D6 PWM, GPIO D6 D6 GPIO, SWCLK 55 PB[3]
D7 PWM, GPIO D7 D7 GPIO, SWDIO 54 PA[27]
MISO / D11 SPI MISO, GPIO S1 / D16 S1 GPIO, PWM, SPI MISO, Serial3 RX. (Was P1S1 on P1.) 41 PA[13]
MOSI / D12 SPI MOSI, GPIO S0 / D15 S0 GPIO, PWM, SPI MOSI, Serial3 TX. (Was P1S0 on P1.) 40 PA[12]
RX / D10 Serial RX, GPIO RX / D9 Serial1 RX (received data), GPIO 63 PA[8]
SCK / D13 SPI SCK, GPIO S2 / D17 S2 GPIO, SPI SCK, Serial3 RTS. (Was P1S2 on P1.) 42 PA[14]
TX / D09 Serial TX, GPIO TX / D8 Serial1 TX (transmitted data), GPIO 64 PA[7]

SPI1 Preferred

If you need to use SPI1 on the D pins, this mapping is required. The D pins are ordered differently between the Argon and P2, and this affects SPI1.

Argon Pin Name Argon Description P2 Pin Name P2 Description P2 Pin Number MCU
A0 / D19 A0 Analog in, GPIO, PWM A0 / D11 A0 Analog in, GPIO 50 PB[1]
A1 / D18 A1 Analog in, GPIO, PWM A1 / D12 A1 Analog in, GPIO 43 PB[2]
A2 / D17 A2 Analog in, GPIO, PWM A2 / D13 A2 Analog in, PWM, GPIO 49 PB[7]
A3 / D16 A3 Analog in, GPIO, PWM S3 / D18 S3 GPIO. (Was P1S3 on P1.), SPI SS 44 PB[26]
A4 / D15 A4 Analog in, GPIO, PWM S4 / D19 S4 GPIO. (Was P1S4 on P1.) 47 PA[0]
A5 / D14 A5 Analog in, GPIO, PWM, SPI SS A5 / D14 A5 Analog in, GPIO, PWM. 23 PB[4]
D0 I2C SDA, GPIO D0 / A3 D0 GPIO, PWM, I2C SDA, A3 Analog In 36 PB[6]
D1 I2C SCL, GPIO D1 / A4 D1 GPIO, PWM, I2C SCL, A4 Analog In 35 PB[5]
D2 SPI1 SCK, Wire1 SDA, Serial1 RTS, PWM, GPIO D4 D4 GPIO, Serial2 TX, SPI1 SCK 52 PA[18]
D3 SPI1 MOSI, Wire1 SCL, Serial1 CTS, PWM, GPIO D2 D2 GPIO, Serial2 RTS, SPI1 MOSI 45 PA[16]
D4 SPI1 MISO, PWM, GPIO D3 D3 GPIO, Serial2 CTS, SPI1 MISO 51 PA[17]
D5 PWM, GPIO D5 D5 GPIO, Serial2 RX, SPI1 SS 53 PA[19]
D6 PWM, GPIO D6 D6 GPIO, SWCLK 55 PB[3]
D7 PWM, GPIO D7 D7 GPIO, SWDIO 54 PA[27]
MISO / D11 SPI MISO, GPIO S1 / D16 S1 GPIO, PWM, SPI MISO, Serial3 RX. (Was P1S1 on P1.) 41 PA[13]
MOSI / D12 SPI MOSI, GPIO S0 / D15 S0 GPIO, PWM, SPI MOSI, Serial3 TX. (Was P1S0 on P1.) 40 PA[12]
RX / D10 Serial RX, GPIO RX / D9 Serial1 RX (received data), GPIO 63 PA[8]
SCK / D13 SPI SCK, GPIO S2 / D17 S2 GPIO, SPI SCK, Serial3 RTS. (Was P1S2 on P1.) 42 PA[14]
TX / D09 Serial TX, GPIO TX / D8 Serial1 TX (transmitted data), GPIO 64 PA[7]

Full module pin comparison

3V3

Argon P2
Pin Number 2 26
Pin Name 3V3 3V3
Description Regulated 3.3V DC output, maximum load 1000 mA 3.3V power to MCU

3V3_IO

Added to P2
Pin Number 5
Pin Name 3V3_IO
Description 3.3V power to MCU IO.

3V3_RF

Added to P2
Pin Number 2
Pin Name 3V3_RF
Description 3.3V power to RF module

A1

Argon P2
Pin Number 6 43
Pin Name A1 A1
Pin Alternate Name D18 D12
Description A1 Analog in, GPIO, PWM A1 Analog in, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone A0, A1, A2, and A3 must have the same frequency. No
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

A3

Argon P2
Pin Number 8 36
Pin Name A3 D0
Pin Alternate Name D16 A3
Description A3 Analog in, GPIO, PWM D0 GPIO, PWM, I2C SDA, A3 Analog In
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone A0, A1, A2, and A3 must have the same frequency. Yes
I2C interface n/a SDA. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 22K

A4

Argon P2
Pin Number 9 35
Pin Name A4 D1
Pin Alternate Name D15 A4
Description A4 Analog in, GPIO, PWM D1 GPIO, PWM, I2C SCL, A4 Analog In
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone A4, A5, D2, and D3 must have the same frequency. Yes
I2C interface n/a SCL. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 22K

A5

Argon P2
Pin Number 10 23
Pin Name A5 A5
Pin Alternate Name D14 D14
Description A5 Analog in, GPIO, PWM, SPI SS A5 Analog in, GPIO, PWM.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone A4, A5, D2, and D3 must have the same frequency. Yes
SPI interface SS. Use SPI object. This is only the default SS/CS pin, you can use any GPIO instead. n/a
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 42K

D0

Argon P2
Pin Number 16 36
Pin Name D0 D0
Pin Alternate Name n/a A3
Description I2C SDA, GPIO D0 GPIO, PWM, I2C SDA, A3 Analog In
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
Supports analogWrite (PWM) No Yes
Supports tone No Yes
I2C interface SDA. Use Wire object. SDA. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 22K

D1

Argon P2
Pin Number 17 35
Pin Name D1 D1
Pin Alternate Name n/a A4
Description I2C SCL, GPIO D1 GPIO, PWM, I2C SCL, A4 Analog In
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
Supports analogWrite (PWM) No Yes
Supports tone No Yes
I2C interface SCL. Use Wire object. SCL. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 22K

D11

Argon P2
Pin Number 13 50
Pin Name MISO A0
Pin Alternate Name D11 D11
Description SPI MISO, GPIO A0 Analog in, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
SPI interface MISO. Use SPI object. n/a
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D12

Argon P2
Pin Number 12 43
Pin Name MOSI A1
Pin Alternate Name D12 D12
Description SPI MOSI, GPIO A1 Analog in, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
SPI interface MOSI. Use SPI object. n/a
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D13

Argon P2
Pin Number 11 49
Pin Name SCK A2
Pin Alternate Name D13 D13
Description SPI SCK, GPIO A2 Analog in, PWM, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
Supports analogWrite (PWM) No Yes
Supports tone No Yes
SPI interface SCK. Use SPI object. n/a
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 42K

D17

Argon P2
Pin Number 7 42
Pin Name A2 S2
Pin Alternate Name D17 D17
Description A2 Analog in, GPIO, PWM S2 GPIO, SPI SCK, Serial3 RTS. (Was P1S2 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports analogWrite (PWM) Yes No
Supports tone A0, A1, A2, and A3 must have the same frequency. No
UART serial n/a RTS. Use Serial3 object. Flow control optional.
SPI interface n/a SCK. Use SPI object.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D19

Argon P2
Pin Number 5 47
Pin Name A0 S4
Pin Alternate Name D19 D19
Description A0 Analog in, GPIO, PWM S4 GPIO. (Was P1S4 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports analogWrite (PWM) Yes No
Supports tone A0, A1, A2, and A3 must have the same frequency. No
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 22K. No internal pull up or pull down in HIBERNATE sleep mode.

D2

Argon P2
Pin Number 18 45
Pin Name D2 D2
Description SPI1 SCK, Wire1 SDA, Serial1 RTS, PWM, GPIO D2 GPIO, Serial2 RTS, SPI1 MOSI
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone A4, A5, D2, and D3 must have the same frequency. No
UART serial Options RTS hardware flow control for Serial1 RTS. Use Serial2 object. Flow control optional.
SPI interface SCK. Use SPI1 object. MOSI. Use SPI1 object.
I2C interface SDA. Use Wire1 object. n/a
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D3

Argon P2
Pin Number 19 51
Pin Name D3 D3
Description SPI1 MOSI, Wire1 SCL, Serial1 CTS, PWM, GPIO D3 GPIO, Serial2 CTS, SPI1 MISO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone A4, A5, D2, and D3 must have the same frequency. No
UART serial Options CTS hardware flow control for Serial1 CTS. Use Serial2 object. Flow control optional.
SPI interface MOSI. Use SPI1 object. MISO. Use SPI1 object.
I2C interface SCL. Use Wire1 object. n/a
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D4

Argon P2
Pin Number 20 52
Pin Name D4 D4
Description SPI1 MISO, PWM, GPIO D4 GPIO, Serial2 TX, SPI1 SCK
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone D4, D5, D6, and D7 must have the same frequency. No
UART serial n/a TX. Use Serial2 object.
SPI interface MISO. Use SPI1 object. SCK. Use SPI1 object.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D5

Argon P2
Pin Number 21 53
Pin Name D5 D5
Description PWM, GPIO D5 GPIO, Serial2 RX, SPI1 SS
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone D4, D5, D6, and D7 must have the same frequency. No
UART serial n/a RX. Use Serial2 object.
SPI interface n/a SS. Use SPI1 object. Can use any pin for SPI1 SS/CS however.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

D6

Argon P2
Pin Number 22 55
Pin Name D6 D6
Description PWM, GPIO D6 GPIO, SWCLK
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone D4, D5, D6, and D7 must have the same frequency. No
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 42K
SWD interface n/a SWCLK. 40K pull-down at boot.
Signal used at boot n/a SWCLK. 40K pull-down at boot.

D7

Argon P2
Pin Number 23 54
Pin Name D7 D7
Description PWM, GPIO D7 GPIO, SWDIO
Supports digitalRead Yes Yes.
Supports digitalWrite Yes Yes. On the Photon this is the blue D7 LED.
Supports analogWrite (PWM) PWM is shared with the RGB LED, you can specify a different duty cycle but should not change the frequency. No
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 42K
SWD interface n/a SWDIO. 40K pull-up at boot.
Signal used at boot n/a SWDIO. 40K pull-up at boot. Low at boot triggers MCU test mode.

EN

Removed from Argon
Pin Number 26
Pin Name EN
Description Power supply enable. Connect to GND to power down. Has internal weak (100K) pull-up.

GND

Argon P2
Pin Number 4 1
Pin Name GND GND
Description Ground. Ground. Be sure you connect all P1 ground pins.

LI+

Removed from Argon
Pin Number 27
Pin Name LI+
Description Connected to JST PH LiPo battery connector. 3.7V in or out.

MODE

Argon P2
Pin Number 3 46
Pin Name MODE MODE
Pin Alternate Name D20 n/a
Description MODE button, has internal pull-up MODE button. Pin number constant is BTN. External pull-up required!
Supports attachInterrupt n/a Yes

NC

Added to P2
Pin Number 7
Pin Name NC
Description No connection. Do not connect anything to this pin.

RGBB

Added to P2
Pin Number 31
Pin Name RGBB
Description RGB LED Blue
Supports attachInterrupt Yes

RGBG

Added to P2
Pin Number 32
Pin Name RGBG
Description RGB LED Green
Supports attachInterrupt Yes

RGBR

Added to P2
Pin Number 29
Pin Name RGBR
Description RGB LED Red
Supports attachInterrupt Yes

RST

Argon P2
Pin Number 1 34
Pin Name RST RST
Description Hardware reset. Pull low to reset; can leave unconnected in normal operation. Hardware reset. Pull low to reset; can leave unconnected in normal operation.

RX

Argon P2
Pin Number 14 30
Pin Name RX D10
Pin Alternate Name D10 WKP
Description Serial RX, GPIO D10 GPIO, Serial 3 CTS. (Was WKP/A7 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial RX Use Serial1 object. CTS. Use Serial3 object. Flow control optional.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

RX

Added to P2
Pin Number 63
Pin Name RX
Pin Alternate Name D9
Description Serial1 RX (received data), GPIO
Supports digitalRead Yes
Supports digitalWrite Yes
UART serial RX. Use Serial1 object.
Supports attachInterrupt Yes
Internal pull-up or pull-down resistance 42K

S0

Added to P2
Pin Number 40
Pin Name S0
Pin Alternate Name D15
Description S0 GPIO, PWM, SPI MOSI, Serial3 TX. (Was P1S0 on P1.)
Supports digitalRead Yes
Supports digitalWrite Yes
Supports analogWrite (PWM) Yes
Supports tone Yes
UART serial TX. Use Serial3 object.
SPI interface MOSI. Use SPI object.
Supports attachInterrupt Yes
Internal pull-up or pull-down resistance 2.1K

S1

Added to P2
Pin Number 41
Pin Name S1
Pin Alternate Name D16
Description S1 GPIO, PWM, SPI MISO, Serial3 RX. (Was P1S1 on P1.)
Supports digitalRead Yes
Supports digitalWrite Yes
Supports analogWrite (PWM) Yes
Supports tone Yes
UART serial RX. Use Serial3 object.
SPI interface MISO. Use SPI object.
Supports attachInterrupt Yes
Internal pull-up or pull-down resistance 2.1K

S3

Added to P2
Pin Number 44
Pin Name S3
Pin Alternate Name D18
Description S3 GPIO. (Was P1S3 on P1.), SPI SS
Supports digitalRead Yes
Supports digitalWrite Yes
SPI interface Default SS for SPI.
Supports attachInterrupt Yes
Internal pull-up or pull-down resistance 2.1K

S5

Added to P2
Pin Number 48
Pin Name S5
Pin Alternate Name D20
Description S5 GPIO. (Was P1S5 on P1.)
Supports digitalWrite Yes
Supports attachInterrupt Yes
Internal pull-up or pull-down resistance 22K. No internal pull up or pull down in HIBERNATE sleep mode

S6

Added to P2
Pin Number 33
Pin Name S6
Pin Alternate Name D21
Description S6 GPIO. (Was P1S6/TESTMODE on P1.)
Supports digitalRead Yes
Supports digitalWrite Yes
Supports attachInterrupt Yes
Internal pull-up or pull-down resistance 22K. No internal pull up or pull down in HIBERNATE sleep mode.

TX

Argon P2
Pin Number 15 64
Pin Name TX TX
Pin Alternate Name D09 D8
Description Serial TX, GPIO Serial1 TX (transmitted data), GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial TX Use Serial1 object. TX. Use Serial1 object.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 42K
Signal used at boot n/a Low at boot triggers ISP flash download

USBDATA-

Added to P2
Pin Number 62
Pin Name USBDATA-
Description USB Data-
Input is 5V Tolerant Yes

USBDATA+

Added to P2
Pin Number 61
Pin Name USBDATA+
Description USB Data+
Input is 5V Tolerant Yes

VBAT_MEAS

Added to P2
Pin Number 12
Pin Name VBAT_MEAS
Description Battery voltage measurement (optional).

VUSB

Removed from Argon
Pin Number 25
Pin Name VUSB
Description Power out (when powered by USB) 5 VDC at 1A maximum. Power in with limitations.
Input is 5V Tolerant Yes

WKP

Argon P2
Pin Number 24 30
Pin Name D8 D10
Pin Alternate Name WKP WKP
Description GPIO, PWM D10 GPIO, Serial 3 CTS. (Was WKP/A7 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone D4, D5, D6, and D7 must have the same frequency. No
UART serial n/a CTS. Use Serial3 object. Flow control optional.
Supports attachInterrupt Yes. You can only have 8 active interrupt pins. Yes
Internal pull-up or pull-down resistance 13K 2.1K

Software

Wi-Fi Configuration

The P2 and Argon utilize BLE or USB for configuration of Wi-Fi rather than the SoftAP approach taken with the P1. Wi-Fi setup for the P2 should be very similar to the Argon.

Feature P2 P1 Argon
Wi-Fi (SoftAP)
BLE

User firmware binary size

One major advantage of the P2 is that user firmware binaries can be up to 2048 Kbytes.

On the Argon (Device OS 3.1 and later), it's 256 Kbytes, or 128 Kbytes for older version of Device OS.

Platform ID

The Platform ID of the P2 (32, PLATFORM_P2) is different from that of the Argon (12) because of the vastly different hardware.

If you have a product based on the Argon, you will need to create a separate product for devices using the P2. While you may be able to use the same source code to build your application, the firmware binaries uploaded to the console will be different, so they need to be separate products. This generally does not affect billing as only the number of devices, not the number of products, is counted toward your plan limits.

Third-party libraries

Most third-party libraries are believed to be compatible. The exceptions include:

  • Libraries for MCU-specific features (such as ADC DMA)
  • Libraries that are hardcoded to support only certain platforms by their PLATFORM_ID

Version History

Revision Date Author Comments
pre 2022-04-06 RK Pre-release
2022-04-08 RK Added recommended pin mappings
2022-04-12 RK Added serial baud rates
2022-07-14 RK No hardware pull-up on MODE pin
2022-07-18 RK List which pins have which pull-up or pull-down value
2022-08-12 RK Warning about BLE central mode not available