P2 from P1 migration guide

Pre-release version 2022-03-14

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

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 Argon
User application size 2048 KB (2 MB) 128 KB 256 KB
Flash file system1 2 MB 2 MB
MCU RTL8721DM STM32F205RGY6 nRF52840
Realtek Semiconductor ST Microelectronics Nordic Semiconductor
CPU Cortex M33 @ 200 MHz Cortex M3 @ 120 MHz Cortex M3 @ 64 MHz
Cortex M23 @ 20 MHz
RAM2 512 KB 128 KB 256 KB
Flash3 16 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
  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 Separate Wi-Fi and BLE antennas
Built-in PCB antenna (Wi-Fi & BLE) Built-in PCB 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 (BLE)4
Peripherals USB 2.0 USB 1.1 USB 1.1
Digital GPIO 22 24 20
Analog (ADC) 6 13 6
Analog (DAC) 2
UART 3 2 1
SPI 2 2 2
PWM 6 12 8
I2C 1 1 1
CAN 1
I2S 1 1
JTAG
SWD

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.

Hardware

No 5V tolerance!

On Gen 2 devices (STM32F205), most pins are 5V tolerant. This is not the case for Gen 3 (nRF52840) and the P2 (RTL872x). You must not exceed 3.3V on any GPIO pin, including ports such as serial, I2C, and SPI.

Pins A3, A4, and DAC (A6)

Pins A3 (module pin 22), A4 (module pin 21), DAC/A6 (module pin 24) do not exist on the P2 and are NC.

You will need to use different pins if you are currently using these pins.

SPI

Both the P1 and P2 have two SPI ports, however the pins are different for SPI (primary SPI).

P1 P2
SPI SCK A3 D20 / S2
SPI MISO A4 D19 / S1
SPI MOSI A5 D18 / S0

The following are all SPI-related pins on the P1 and P2:

Pin P1 Pin Name P1 SPI P2 Pin Name P2 SPI
21 A4 SPI (MISO) NC  
22 A3 SPI (SCK) NC  
23 A5 SPI (MOSI) A5 / D14  
40 P1S0   S0 / D15 SPI (MOSI)
41 P1S1   S1 / D16 SPI (MISO)
42 P1S2   S2 / D17 SPI (SCK)
44 P1S3   S3 / D18 SPI (SS)
45 D2 SPI1 (MOSI) D2 SPI1 (MOSI)
49 A2 SPI (SS) A2 / D13  
51 D3 SPI1 (MISO) D3 SPI1 (MISO)
52 D4 SPI1 (SCK) D4 SPI1 (SCK)
53 D5 SPI1 (SS) D5 SPI1 (SS)

SPI - Gen 2 devices (including P1)

SPI SPI1
Maximum rate 30 MHz 15 MHz
Default rate 15 MHz 15 MHz
Clock 60 MHz 30 MHz
  • Available clock divisors: 2, 4, 8, 16, 32, 64, 128, 256

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 P1:

Pin P1 Pin Name P1 I2C P2 Pin Name P2 I2C
35 D1 Wire (SCL) D1 / A4 Wire (SCL)
36 D0 Wire (SDA) D0 / A3 Wire (SDA)
  • The P2 I2C port is not 5V tolerant
  • The P1 includes internal 2.2K pull-up resistors on D0/D1, the P2 does not

Serial (UART)

The primary UART serial (Serial1) is on the TX and RX pins on both the P1 and P2. There is no hardware flow control on this port on the P1 or P2.

The secondary UART serial (Serial2) is on different pins, however it does not conflict with the RGB LED, and also supports CTS/RTS hardware flow control.

There is also a third UART serial (Serial3).

Pin P1 Pin Name P1 Serial P2 Pin Name P2 Serial
30 WKP / A7   D10 / WKP Serial3 (CTS)
31 RGBB Serial2 (RX) RGBB  
32 RGBG Serial2 (TX) RGBG  
40 P1S0   S0 / D15 Serial3 (TX)
41 P1S1   S1 / D16 Serial3 (RX)
42 P1S2   S2 / D17 Serial3 (RTS)
45 D2   D2 Serial2 (RTS)
51 D3   D3 Serial2 (CTS)
52 D4   D4 Serial2 (TX)
53 D5   D5 Serial2 (RX)
63 RX Serial1 (RX) RX / D9 Serial1 (RX)
64 TX Serial1 (TX) TX / D8 Serial1 (TX)
P1 P2
Buffer size 64 bytes 2048 bytes
7-bit mode
8-bit mode
9-bit mode
1 stop bit
2 stop bits
No parity
Even parity
Odd parity
Break detection
LIN bus support
Half duplex
CTS/RTS flow control 1

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

Supported Baud Rates:

Baud Rate P1 P2
110
300
600
1200
2400
4800
9600
14400
19200
28800
38400
57600
76800
115200
128000
153600
230400
500000
921600
1000000
1382400
1444400
1500000
1843200
2000000
2100000
2764800
3000000
3250000
3692300
3750000
4000000
6000000

Analog input (ADC)

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

Pin P1 Pin Name P1 ADC P2 Pin Name P2 ADC
21 A4 NC  
22 A3 NC  
23 A5 A5 / D14
24 DAC / A6 NC  
30 WKP / A7 D10 / WKP  
35 D1   D1 / A4
36 D0   D0 / A3
40 P1S0 S0 / D15  
41 P1S1 S1 / D16  
42 P1S2 S2 / D17  
43 A1 A1 / D12
44 P1S3 S3 / D18  
48 P1S5 S5 / D20  
49 A2 A2 / D13
50 A0 A0 / D11

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 P1 and P2.

Pin P1 Pin Name P1 PWM P2 Pin Name P2 PWM
21 A4 NC  
23 A5 A5 / D14
30 WKP / A7 D10 / WKP  
33 P1S6 S6 / D21  
35 D1 D1 / A4
36 D0 D0 / A3
40 P1S0 S0 / D15
41 P1S1 S1 / D16
45 D2 D2  
49 A2   A2 / D13
51 D3 D3  
63 RX RX / D9  
64 TX TX / D8  

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.

Digital to analog converter (DAC)

The P1 supports DAC one A3 and A6 (DAC). There is no DAC on the P2 or Gen 3 devices.

If you need a DAC, it's easy to add one via I2C or SPI on your base board.

Pin P1 Pin Name P1 DAC P2 Pin Name P2 DAC
22 A3 NC  
24 DAC / A6 NC  

WKP (A7)

P1 P2
Module Pin 30 30
Pin Name WKP WKP
A7 D11
Analog Input
PWM

On Gen 2 devices (STM32), only the WKP pin can wake from HIBERNATE sleep mode.

This restriction does not exist on the P2 and Gen 3 devices; any pin can be used to wake from all sleep modes.

CAN (Controller Area Network)

The P1 supports CAN on pins D1 and D2. There is no CAN on the P2 or Gen 3 devices (except the Tracker).

  • The Tracker SoM includes CAN via a MCP25625 CAN interface with integrated transceiver.
  • Both the MCP2515 and MCP25625 work with the library used on the Tracker and can be used to add CAN to the P2.
Pin P1 Pin Name P1 CAN P2 Pin Name P2 CAN
35 D1 D1 / A4  
45 D2 D2  

I2S (Sound)

The P1 theoretically had I2S sound available on pins D1 and D2, however there has never been support for it in Device OS.

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

Pin P1 Pin Name P1 I2S P2 Pin Name P2 I2S
45 D2 I2S3_SD D2  
46 MODE I2S3_MCK MODE  
52 D4 I2S3_SCK D4  
53 D5 I2S3_WS D5  

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.
  • On the P1, the internal pull is approximately 40K.

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.

The P1 had an internal weak pull-up.

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]

Interrupts

There are many limitations for interrupts on the STM32F205. All pins can be used for interrupts on Gen 3 devices and the P2.

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 P1, the internal pull is approximately 40K.
  • The P1 module has 2.1K pull-ups on D0 and D1 (I2C), separate from the MCU pull-ups. The P2 does not have extra hardware pull-ups.

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

The P1 did not have a flash file system.

The P2 has 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 P1 and P2.

The P1 had 2047 bytes of emulated EEPROM. The P2 has 4096 bytes of emulated EEPROM. On the P2 and Gen 3 devices, the EEPROM is actually just a file on the flash file system.

Pin functions removed

The following pins served P1-specific uses and are NC on the P2. You should not connect anything to these pins.

Pin Pin Name Description
7 WL_REG_ON BCM43362 Debugging Pin.
16 WL_JTAG_TDI BCM43362 Debugging Pin.
17 WL_JTAG_TCK BCM43362 Debugging Pin.
18 WL_JTAG_TRSTN BCM43362 Debugging Pin.
19 WL_JTAG_TMS BCM43362 Debugging Pin.
20 WL_JTAG_TDO BCM43362 Debugging Pin.
21 A4 A4 Analog in, GPIO, SPI.
22 A3 A3 True analog out, analog in, GPIO.
24 DAC / A6 DAC/A6 True analog out, analog in, GPIO.
38 VBAT Battery for internal real-time clock, backup registers, and SRAM. Supply 1.65VDC to 3.6 VDC at 19 μA..
56 BTCX_STATUS Coexistence signal: Bluetooth status and TX/RX direction.
57 BTCX_RF_ACTIVE Coexistence signal: Bluetooth is active.
58 BTCX_TXCONF Output giving Bluetooth permission to TX.
60 WL_SLEEP_CLK BCM43362 Debugging Pin

Pin functions added

The following pins were NC on the P1 but are used on the P2.

Pin Pin Name Description
12 VBAT_MEAS Battery voltage measurement (optional).

Full module pin comparison

Module Pin 1 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 2 (VBAT_WL / 3V3_RF)

P1 P2
Pin Name VBAT_WL 3V3_RF
Description Battery for BCM43362. 3.3V power to RF module

Module Pin 3 (VBAT_WL / 3V3_RF)

P1 P2
Pin Name VBAT_WL 3V3_RF
Description Battery for BCM43362. 3.3V power to RF module

Module Pin 4 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 5 (VDDIO_3V3_WL / 3V3_IO)

P1 P2
Pin Name VDDIO_3V3_WL 3V3_IO
Description Regulated 3.3V DC power input for BCM43362. 3.3V power to MCU IO.

Module Pin 6 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 7 (WL_REG_ON / NC)

P1 P2
Pin Name WL_REG_ON NC
Description BCM43362 Debugging Pin. No connection. Do not connect anything to this pin.

Module Pin 8 (NC)

Unchanged between P1 and P2
Pin Name NC
Description No connection. Do not connect anything to this pin.

Module Pin 9 (NC)

Unchanged between P1 and P2
Pin Name NC
Description No connection. Do not connect anything to this pin.

Module Pin 10 (NC)

Unchanged between P1 and P2
Pin Name NC
Description No connection. Do not connect anything to this pin.

Module Pin 11 (NC)

Unchanged between P1 and P2
Pin Name NC
Description No connection. Do not connect anything to this pin.

Module Pin 12 (NC / VBAT_MEAS)

P1 P2
Pin Name NC VBAT_MEAS
Description No connection. Do not connect anything to this pin. Battery voltage measurement (optional).

Module Pin 13 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 14 (NC)

Unchanged between P1 and P2
Pin Name NC
Description No connection. Do not connect anything to this pin.

Module Pin 15 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 16 (WL_JTAG_TDI / NC)

P1 P2
Pin Name WL_JTAG_TDI NC
Description BCM43362 Debugging Pin. No connection. Do not connect anything to this pin.

Module Pin 17 (WL_JTAG_TCK / NC)

P1 P2
Pin Name WL_JTAG_TCK NC
Description BCM43362 Debugging Pin. No connection. Do not connect anything to this pin.

Module Pin 18 (WL_JTAG_TRSTN / NC)

P1 P2
Pin Name WL_JTAG_TRSTN NC
Description BCM43362 Debugging Pin. No connection. Do not connect anything to this pin.

Module Pin 19 (WL_JTAG_TMS / NC)

P1 P2
Pin Name WL_JTAG_TMS NC
Description BCM43362 Debugging Pin. No connection. Do not connect anything to this pin.

Module Pin 20 (WL_JTAG_TDO / NC)

P1 P2
Pin Name WL_JTAG_TDO NC
Description BCM43362 Debugging Pin. No connection. Do not connect anything to this pin.

Module Pin 21 (A4 / NC)

P1 P2
Pin Name A4 NC
Description A4 Analog in, GPIO, SPI. No connection. Do not connect anything to this pin.
Supports digitalRead Yes n/a
Supports digitalWrite Yes n/a
Supports analogRead Yes n/a
Supports analogWrite (PWM) Yes. D3 and A4 share the same PWM channel and the PWM duty cycle is set for both. n/a
Supports tone Yes. D3 and A4 share the same PWM channel and only one frequency can be set for both. n/a
SPI interface MISO. Use SPI object. n/a
Supports attachInterrupt Yes. D1 and A4 share the same interrupt handler. n/a
Internal pull-up or pull-down resistance 40K n/a
Input is 5V Tolerant Yes n/a

Module Pin 22 (A3 / NC)

P1 P2
Pin Name A3 NC
Description A3 True analog out, analog in, GPIO. No connection. Do not connect anything to this pin.
Supports digitalRead Yes n/a
Supports digitalWrite Yes n/a
Supports analogRead Yes n/a
Supports analogWrite (DAC) Yes n/a
SPI interface SCK. Use SPI object. n/a
Supports attachInterrupt Yes. D2, A0, and A3 share the same interrupt handler. n/a
Internal pull-up or pull-down resistance 40K n/a

Module Pin 23 (A5)

P1 P2
Pin Name A5 A5
Pin Alternate Name n/a D14
Description A5 Analog in, GPIO, SPI. A5 Analog in, GPIO, PWM.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes. D2 and A5 share the same PWM channel and the PWM duty cycle is set for both. Yes
Supports tone Yes. D2 and A5 share the same PWM channel and only one frequency can be set for both. Yes
SPI interface MOSI. Use SPI object. n/a
Supports attachInterrupt No Yes
Internal pull-up or pull-down resistance 40K 42K
Input is 5V Tolerant Yes No

Module Pin 24 (DAC / NC)

P1 P2
Pin Name DAC NC
Pin Alternate Name A6 n/a
Description DAC/A6 True analog out, analog in, GPIO. No connection. Do not connect anything to this pin.
Supports digitalRead Yes n/a
Supports digitalWrite Yes n/a
Supports analogRead Yes n/a
Supports analogWrite (DAC) Yes n/a
Supports attachInterrupt Yes. D3, DAC/A6, and P1S3 share the same interrupt handler. n/a
Internal pull-up or pull-down resistance 40K n/a

Module Pin 25 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 26 (3V3)

Unchanged between P1 and P2
Pin Name 3V3
Description 3.3V power to MCU

Module Pin 27 (3V3)

Unchanged between P1 and P2
Pin Name 3V3
Description 3.3V power to MCU

Module Pin 28 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 29 (RGBR)

P1 P2
Pin Name RGBR RGBR
Description RGB LED Red RGB LED Red
Supports attachInterrupt n/a Yes
Input is 5V Tolerant No, if LED is connected. No

Module Pin 30 (WKP / D10)

P1 P2
Pin Name WKP D10
Pin Alternate Name A7 WKP
Description WKP/A7 Wakeup (active high), analog in, GPIO. D10 GPIO, Serial 3 CTS. (Was WKP/A7 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes n/a
Supports analogWrite (PWM) Yes No
Supports tone Yes No
UART serial n/a CTS. Use Serial3 object. Flow control optional.
Supports attachInterrupt Yes. WKP/A7, P1S0, and P1S2 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 31 (RGBB)

P1 P2
Pin Name RGBB RGBB
Description RGB LED Blue RGB LED Blue
UART serial RX. Use Serial2 object. n/a
Supports attachInterrupt n/a Yes
Input is 5V Tolerant No, if LED is connected. No

Module Pin 32 (RGBG)

P1 P2
Pin Name RGBG RGBG
Description RGB LED Green RGB LED Green
UART serial TX. Use Serial2 object. n/a
Supports attachInterrupt n/a Yes
Input is 5V Tolerant No, if LED is connected. No

Module Pin 33 (P1S6 / S6)

P1 P2
Pin Name P1S6 S6
Pin Alternate Name n/a D21
Description P1S6 GPIO S6 GPIO. (Was P1S6/TESTMODE on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone Yes No
Supports attachInterrupt Yes Yes
Internal pull-up or pull-down resistance 40K 22K. No internal pull up or pull down in HIBERNATE sleep mode.

Module Pin 34 (RST)

Unchanged between P1 and P2
Pin Name RST
Description Hardware reset. Pull low to reset; can leave unconnected in normal operation.

Module Pin 35 (D1)

P1 P2
Pin Name D1 D1
Pin Alternate Name n/a A4
Description D1 GPIO, I2C, CAN D1 GPIO, PWM, I2C SCL, A4 Analog In
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
I2C interface SCL. Use Wire object. There is a 2.1K hardware pull-up on the P1 module. Is 5V tolerant. SCL. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt Yes. D1 and A4 share the same interrupt handler. Yes
CAN interface CAN2_TX n/a
Internal pull-up or pull-down resistance 40K 22K
Input is 5V Tolerant Yes No

Module Pin 36 (D0)

P1 P2
Pin Name D0 D0
Pin Alternate Name n/a A3
Description D0 GPIO, I2C D0 GPIO, PWM, I2C SDA, A3 Analog In
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead No Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
I2C interface SDA. Use Wire object. There is a 2.1K hardware pull-up on the P1 module. Is 5V tolerant. SDA. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt No Yes
Internal pull-up or pull-down resistance 40K 22K
Input is 5V Tolerant Yes No

Module Pin 37 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 38 (VBAT / NC)

P1 P2
Pin Name VBAT NC
Description Battery for internal real-time clock, backup registers, and SRAM. Supply 1.65VDC to 3.6 VDC at 19 μA.. No connection. Do not connect anything to this pin.

Module Pin 39 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 40 (P1S0 / S0)

P1 P2
Pin Name P1S0 S0
Pin Alternate Name n/a D15
Description P1S0 Analog in, GPIO, PWM. S0 GPIO, PWM, SPI MOSI, Serial3 TX. (Was P1S0 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports analogWrite (PWM) Yes Yes
Supports tone Yes. Yes
UART serial n/a TX. Use Serial3 object.
SPI interface n/a MOSI. Use SPI object.
Supports attachInterrupt Yes. WKP/A7, P1S0, and P1S2 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 41 (P1S1 / S1)

P1 P2
Pin Name P1S1 S1
Pin Alternate Name n/a D16
Description P1S1 Analog in, GPIO, PWM. S1 GPIO, PWM, SPI MISO, Serial3 RX. (Was P1S1 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports analogWrite (PWM) Yes Yes
Supports tone Yes. Yes
UART serial n/a RX. Use Serial3 object.
SPI interface n/a MISO. Use SPI object.
Supports attachInterrupt Yes. P1S1 and P1S5 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 42 (P1S2 / S2)

P1 P2
Pin Name P1S2 S2
Pin Alternate Name n/a D17
Description P1S2 Analog in, GPIO S2 GPIO, SPI SCK, Serial3 RTS. (Was P1S2 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
UART serial n/a RTS. Use Serial3 object. Flow control optional.
SPI interface n/a SCK. Use SPI object.
Supports attachInterrupt Yes. WKP/A7, P1S0, and P1S2 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 43 (A1)

P1 P2
Pin Name A1 A1
Pin Alternate Name n/a D12
Description A1 Analog in, GPIO A1 Analog in, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports attachInterrupt Yes. D4 and A1 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 44 (P1S3 / S3)

P1 P2
Pin Name P1S3 S3
Pin Alternate Name n/a D18
Description P1S3 Analog in, GPIO S3 GPIO. (Was P1S3 on P1.), SPI SS
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
SPI interface n/a Default SS for SPI.
Supports attachInterrupt Yes. D3, DAC/A6, and P1S3 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 45 (D2)

P1 P2
Pin Name D2 D2
Description D2 GPIO, SPI1, CAN D2 GPIO, Serial2 RTS, SPI1 MOSI
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes. D2 and A5 share the same PWM channel and the PWM duty cycle is set for both. No
Supports tone Yes. D2 and A5 share the same PWM channel and only one frequency can be set for both. No
UART serial n/a RTS. Use Serial2 object. Flow control optional.
SPI interface MOSI. Use SPI1 object. MOSI. Use SPI1 object.
Supports attachInterrupt Yes. D2, A0, and A3 share the same interrupt handler. Yes
CAN interface CAN2_RX n/a
I2S interface I2S3_SD n/a
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 46 (MODE)

P1 P2
Pin Name MODE MODE
Description MODE button, has internal pull-up. Pin number constant is BTN. MODE button. Pin number constant is BTN. External pull-up required!
Supports attachInterrupt n/a Yes
I2S interface I2S3_MCK n/a

Module Pin 47 (P1S4 / S4)

P1 P2
Pin Name P1S4 S4
Pin Alternate Name n/a D19
Description P1S4 GPIO S4 GPIO. (Was P1S4 on P1.)
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports attachInterrupt Yes. D7 and P1S4 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 22K. No internal pull up or pull down in HIBERNATE sleep mode.
Input is 5V Tolerant Yes No

Module Pin 48 (P1S5 / S5)

P1 P2
Pin Name P1S5 S5
Pin Alternate Name n/a D20
Description P1S5 Analog in, GPIO S5 GPIO. (Was P1S5 on P1.)
Supports digitalRead Yes No
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports attachInterrupt Yes. P1S1 and P1S5 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 22K. No internal pull up or pull down in HIBERNATE sleep mode
Input is 5V Tolerant Yes No

Module Pin 49 (A2)

P1 P2
Pin Name A2 A2
Pin Alternate Name n/a D13
Description A2 Analog in, GPIO, SPI SS A2 Analog in, PWM, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) No Yes
Supports tone No 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 Yes
Internal pull-up or pull-down resistance 40K 42K
Input is 5V Tolerant Yes No

Module Pin 50 (A0)

P1 P2
Pin Name A0 A0
Pin Alternate Name n/a D11
Description A0 Analog in, GPIO A0 Analog in, GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports attachInterrupt Yes. D2, A0, and A3 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No

Module Pin 51 (D3)

P1 P2
Pin Name D3 D3
Description D3 GPIO, SPI1 D3 GPIO, Serial2 CTS, SPI1 MISO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes. D3 and A4 share the same PWM channel and the PWM duty cycle is set for both. No
Supports tone Yes. D3 and A4 share the same PWM channel and only one frequency can be set for both. No
UART serial n/a CTS. Use Serial2 object. Flow control optional.
SPI interface MISO. Use SPI1 object. MISO. Use SPI1 object.
Supports attachInterrupt Yes. D3, DAC/A6, and P1S3 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K. Pull-up applied in bootloader for JTAG. 2.1K
Input is 5V Tolerant Yes No
JTAG interface JTAG RST. 40K pull-up at boot. n/a
Signal used at boot JTAG RST. 40K pull-up at boot. n/a

Module Pin 52 (D4)

P1 P2
Pin Name D4 D4
Description D4 GPIO, SPI1 D4 GPIO, Serial2 TX, SPI1 SCK
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial n/a TX. Use Serial2 object.
SPI interface SCK. Use SPI1 object. SCK. Use SPI1 object.
Supports attachInterrupt Yes. D4 and A1 share the same interrupt handler. Yes
I2S interface I2S3_SCK n/a
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No
JTAG interface JTAG TDO. Floating at boot. n/a
Signal used at boot JTAG TDO. Floating at boot. n/a

Module Pin 53 (D5)

P1 P2
Pin Name D5 D5
Description D5 GPIO, SPI1 D5 GPIO, Serial2 RX, SPI1 SS
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial n/a RX. Use Serial2 object.
SPI interface SS. Use SPI1 object. Can use any pin for SPI1 SS/CS however. SS. Use SPI1 object. Can use any pin for SPI1 SS/CS however.
Supports attachInterrupt Yes Yes
I2S interface I2S3_WS n/a
Internal pull-up or pull-down resistance 40K 2.1K
Input is 5V Tolerant Yes No
JTAG interface JTAG TDI. 40K pull-up at boot. n/a
Signal used at boot JTAG TDI. 40K pull-up at boot. n/a

Module Pin 54 (D7)

P1 P2
Pin Name D7 D7
Description D7 GPIO D7 GPIO, SWDIO
Supports digitalRead Yes. Yes.
Supports digitalWrite Yes. On the Photon this is the blue D7 LED. Yes. On the Photon this is the blue D7 LED.
Supports attachInterrupt Yes. D7 and P1S4 share the same interrupt handler. Yes
Internal pull-up or pull-down resistance 40K. Pull-up applied in bootloader for JTAG. 42K
JTAG interface JTAG TMS. 40K pull-up at boot. n/a
SWD interface SWDIO. 40K pull-up at boot. SWDIO. 40K pull-up at boot.
Signal used at boot JTAG TMS/SWDIO. 40K pull-up at boot. SWDIO. 40K pull-up at boot. Low at boot triggers MCU test mode.

Module Pin 55 (D6)

P1 P2
Pin Name D6 D6
Description D6 GPIO D6 GPIO, SWCLK
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports attachInterrupt Yes Yes
Internal pull-up or pull-down resistance 40K. Pull-up applied in bootloader for JTAG. 42K
Input is 5V Tolerant Yes No
JTAG interface JTAG TCK. 40K pull-down at boot. n/a
SWD interface SWCLK. 40K pull-down at boot. SWCLK. 40K pull-down at boot.
Signal used at boot JTAG TCK/SWCLK. 40K pull-down at boot. SWCLK. 40K pull-down at boot.

Module Pin 56 (BTCX_STATUS / NC)

P1 P2
Pin Name BTCX_STATUS NC
Description Coexistence signal: Bluetooth status and TX/RX direction. No connection. Do not connect anything to this pin.

Module Pin 57 (BTCX_RF_ACTIVE / NC)

P1 P2
Pin Name BTCX_RF_ACTIVE NC
Description Coexistence signal: Bluetooth is active. No connection. Do not connect anything to this pin.

Module Pin 58 (BTCX_TXCONF / NC)

P1 P2
Pin Name BTCX_TXCONF NC
Description Output giving Bluetooth permission to TX. No connection. Do not connect anything to this pin.

Module Pin 59 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 60 (WL_SLEEP_CLK / NC)

P1 P2
Pin Name WL_SLEEP_CLK NC
Description BCM43362 Debugging Pin No connection. Do not connect anything to this pin.

Module Pin 61 (USBDATA+)

Unchanged between P1 and P2
Pin Name USBDATA+
Description USB Data+
Input is 5V Tolerant Yes

Module Pin 62 (USBDATA-)

Unchanged between P1 and P2
Pin Name USBDATA-
Description USB Data-
Input is 5V Tolerant Yes

Module Pin 63 (RX)

P1 P2
Pin Name RX RX
Pin Alternate Name n/a D9
Description Serial1 RX (received data), GPIO, PWM. Serial1 RX (received data), GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone Yes No
UART serial RX. Use Serial1 object. RX. Use Serial1 object.
Supports attachInterrupt Yes Yes
Internal pull-up or pull-down resistance 40K 42K
Input is 5V Tolerant Yes No

Module Pin 64 (TX)

P1 P2
Pin Name TX TX
Pin Alternate Name n/a D8
Description Serial1 TX (transmitted data), GPIO, PWM. Serial1 TX (transmitted data), GPIO
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone Yes No
UART serial TX. Use Serial1 object. TX. Use Serial1 object.
Supports attachInterrupt Yes Yes
Internal pull-up or pull-down resistance 40K 42K
Input is 5V Tolerant Yes No
Signal used at boot n/a Low at boot triggers ISP flash download

Module Pin 65 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 66 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 67 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 68 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 69 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 70 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 71 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

Module Pin 72 (GND)

Unchanged between P1 and P2
Pin Name GND
Description Ground. Be sure you connect all P1 ground pins.

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. Using BLE allow mobile apps to more easily set up the device Wi-Fi without having to modify the mobile device's network configuration.

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, instead of 128 Kbytes on Gen 2 devices including the P1.

Flash file system

On the P2 there is a flash file system (2 MB) for storing user data. This is not available on Gen 2 devices including the P1.

Combined and resumable OTA

On the P2, over-the-air (OTA) updates have two features that can improve the speed and reliability of OTA updates:

  • Combined OTA can combine Device OS and user firmware updates into a single binary that requires only one download and one reboot to install.
  • Resumable OTA allows an update to resume from the point it stopped, instead of starting over from the beginning if interrupted.

Increased API field limits

The maximum size of a variable, function parameter, or publish is 1024 bytes on the P2 vs. 864 bytes on P1.

API Field P1 P2
Variable Key 64 64
Variable Data 864 1024
Function Key 64 64
Function Argument 864 1024
Publish/Subscribe Event Name 64 64
Publish/Subscribe Event Data 864 1024

Platform ID

The Platform ID of the P2 (32, PLATFORM_P2) is different from that of the P1 (8) because of the vastly different hardware.

If you have a product based on the P1, 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 that use peripherals that are not present (such as DAC)
  • 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 2021-11-04 RK Pre-release
2022-02-08 RK Corrected D pin aliases for A5 and S0-S6
2022-02-25 RK Changed D pin aliases for D9 - D22, A5 is not SPI MOSI, Serial2 TX and RX were reversed
2022-03-14 RK Minor edits; no functional changes
2022-03-23 RK Add notes about flash file system and EEPROM
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 Added listing of pins used at boot
2022-08-12 RK Warning about BLE central mode not available