E404X Migration Guide

Preliminary pre-release version 2022-05-06

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

This guide assists in the transition from the E Series E402/E404 to the E404X.

Software Differences

User firmware binary size

One major advantage of the E404X is that user firmware binaries can be up to 256 Kbytes, instead of 128 Kbytes on Gen 2 devices including the E Series.

Flash file system

On the E404X and Gen 3 devices, there is a flash file system (2 MB) for storing user data. This is not available on Gen 2 devices.

Combined and resumable OTA

On the E404X and Gen 3 devices, 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 E404X vs. 864 bytes on other E Series models.

API Field E Series E404X
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

Sleep Modes

  • In general, the E404X will use less power in all modes.
  • In HIBERNATE mode, the RTC (real time clock) does not run on the E404X, so you cannot wake by time from HIBERNATE mode (formerly known as SLEEP_MODE_DEEP).
  • However, you can wake by time from ULTRA_LOW_POWER mode, and it uses less power than the E SeriesHIBERNATE mode.
  • On Gen 2 devices, you can only wake from HIBERNATE with a rising signal on WKP (A7). The E404X can wake from HIBERNATE on any pin, rising or falling.
  • On Gen 2 (STM32F205) devices, if you try to go into HIBERNATE mode with WKP already high, the device will go into sleep and will not wake up by time or pin change, essentially rendering it unable to wake until reset manually. This problem does not occur on the E404X and Gen 3 devices.

RTC (Real-time clock)

  • The E Series module has the ability to use an external lithium coin cell or supercap to power the RTC when the MCU is unpowered. This feature does not exist on the E404X.
  • The RTC on the E404X s is not really a real-time clock. It's basically just a counter, and some advanced wakeup features are not possible on the E404X and Gen 3 devices. These features were not enabled by Device OS on Gen 2 devices, either, so this is generally not an issue.
  • On the E404X and Gen 3 devices, in HIBERNATE sleep mode the RTC does not run, so it is not possible to wake by time, and the system clock will not be set until you connect to the cloud again. ULTRA_LOW_POWER is recommended instead.

Hardware differences

MCU

The microcontroller is different in E Series and E404X:

Measure E Series E404X
MCU STM32F205 nRF52840
Manufacturer ST Microelectronics Nordic Semiconductor
Processor ARM Cortex M3 ARM Cortex M4F
Speed 120 MHz 64 MHz
RAM 128 KB 256 KB
Flash (MCU) 1 MB 1 MB
Flash (external)   4 MB1
Hardware floating point  
  • 1Most of this space is reserved by the system and only a portion if it is available to user applications as a flash file system.
  • Not all RAM is available to user applications. The Device OS firmware uses a portion of it.

BLE (Bluetooth LE)

  • Bluetooth LE (BLE 5.0) is supported on the E404X but not E Series (Gen 2).

No 5V tolerance!

On Gen 2 devices (STM32F205), most pins are 5V tolerant. This is not the case for the E404X and Gen 3 (nRF52840). You must not exceed 3.3V on any GPIO pin, including ports such as serial, I2C, and SPI.

Pins no longer available for GPIO

Pin Pin Name Reason
28 B5 NC on E404X
29 B4 NC on E404X
35 D7 SWD debugging SWDIO
36 D6 SWD debugging SWDCLK
38 D4 SWD debugging SWO
39 D3 NC on E404X

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

B0 and B1 should not be used as wake sources

Pin Pin Name
33 B0
32 B1
  • Pins B0 and B1 should not be used as GPIO wake sources.
  • In ULP sleep mode, when used as an input B0 and B1 should be held at the same logic level even if not used as a wake source.
  • On other devices these pins are used as NFC and the circuitry which protects the MCU from surge voltage can cause leakage voltage between these pins when used as GPIO in both operating and sleep modes.

Beware of leakage current

If you have circuitry that can disconnect the nRF52840 MCU 3V3 power, beware of situations where current can leak into GPIO pins from an external supply.

For example, if you have 3V3 disconnect circuitry but have pull-ups to non-disconnected power, when MCU 3V3 is powered down current can flow into the GPIO causing the MCU to not fully power down. This can prevent the MCU from resetting when power is reapplied. It will also cause excess power consumption when powered down.

SPI

  • On the E404X, there are only two SPI ports SPI (A pins) and SPI1 (C pins)
  • E Series SPI1 on the D pins does not exist on the E404X.
  • E Series SPI2 on the C pins is SPI1 on the E404X

The following are all SPI-related pins on the E Series and E404X:

Pin E Series Pin Name E Series SPI E404X Pin Name E404X SPI
21 A5 SPI (MOSI) A5 SPI (MOSI)
22 A4 SPI (MISO) A4 SPI (MISO)
23 A3 SPI (SCK) A3 SPI (SCK)
24 A2 SPI (SS) A2 SPI (SS)
37 D5 SPI1 (SS) D5 SPI1 (SS)
38 D4 SPI1 (SCK) SWO  
39 D3 SPI1 (MISO) NC  
40 D2 SPI1 (MOSI) D2  
46 C3 SPI2 (SCK) C3 SPI1 (SCK)
47 C2 SPI2 (MISO) C2 SPI1 (MISO)
48 C1 SPI2 (MOSI) C1 SPI1 (MOSI)

The following SPI data rates are available:

E Series SPI E Series SPI1 E404X SPI & SPI1
Maximum rate 30 MHz 15 MHz 32 MHz
Default rate 15 MHz 15 MHz 16 MHz
Clock 60 MHz 30 MHz 64 MHz
  • Available clock divisors: 2, 4 (default), 8, 16, 32, 64, 128, 256
  • On the E404X, SPI_MODE_SLAVE is only supported on SPI1 and is limited to 8 MHz

I2C

  • There is one available I2C port on the E404X.
Pin E Series Pin Name E Series I2C E404X Pin Name E404X I2C
41 D1 Wire (SCL) D1 Wire (SCL)
42 D0 Wire (SDA) D0 Wire (SDA)
44 C5 Wire1 (SCL) C5  
45 C4 Wire1 (SDA) C4  
  • On the E Series (other than the E404X), Wire and Wire1 are the same I2C peripheral and you can only use one at a time, so effectively it only has one I2C port.
  • On the E Series (other than the E404X), the built-in pull-up on SDA and SCL is approximately 40K and an external pull-up is required.
  • On the E404X, the built-in pull-up on SDA and SCL is approximately 13K. An external pull-up is recommended.
  • On the E404X, GPIO is 3.3V and is not 5V tolerant. Connecting to a 5V I2C bus requires level shifting.
  • On the E404X, external pull-ups should only be connected to the MCU 3V3 supply. Pulling up to an external supply can cause leakage current into the GPIO pins of the nRF52840 which can prevent it from resetting properly.

Serial (UART)

The primary UART serial (Serial1) is on the TX and RX pins on both the E Series and E404X. There is no hardware flow control on this port on E Series, but it can be enabled on the E404X on pins D0 (CTS) and D1 (RTS).

The E Series has additional serial ports Serial2, Serial4, and Serial5. These are not available on the E404X.

E Series E404X
Buffer size 64 bytes configurable1
7-bit mode
8-bit mode
9-bit mode
Half duplex
LIN bus
CTS/RTS flow control 2

1Default buffer size is 64 bytes but you can configure a larger buffer if desired, limited by available RAM.

2CTS/RTS flow control optional on Serial1.

Pin E Series Pin Name E Series Serial E404X Pin Name E404X Serial
16 TX Serial1 (TX) TX Serial1 (TX)
17 RX Serial1 (RX) RX Serial1 (RX)
41 D1   D1 Serial1 (CTS)
42 D0   D0 Serial1 (RTS)
46 C3 Serial4 TX C3  
47 C2 Serial4 RX C2  
48 C1 Serial5_TX C1  
49 C0 Serial5_RX C0  
52 RGBB Serial2 (RX) RGBB  
53 RGBG Serial2 (TX) RGBG  

Baud rate support

Baud Rate E Series E404X
1200
2400
4800
9600
19200
28800  
38400
57600
76800  
115200
230400
250000  
460800  
921600  
1000000  

Serial configurations

Constant Description E Series E404X
SERIAL_8N1 8 data bits, no parity, 1 stop bit (default)
SERIAL_8N2 8 data bits, no parity, 2 stop bits  
SERIAL_8E1 8 data bits, even parity, 1 stop bit
SERIAL_8E2 8 data bits, even parity, 2 stop bits  
SERIAL_8O1 8 data bits, odd parity, 1 stop bit  
SERIAL_8O2 8 data bits, odd parity, 2 stop bits  
SERIAL_9N1 9 data bits, no parity, 1 stop bit  
SERIAL_9N2 9 data bits, no parity, 2 stop bits  
SERIAL_7O1 7 data bits, odd parity, 1 stop bit  
SERIAL_7O2 7 data bits, odd parity, 1 stop bit  
SERIAL_7E1 7 data bits, even parity, 1 stop bit  
SERIAL_7E2 7 data bits, even parity, 1 stop bit  
LIN_MASTER_13B 8 data bits, no parity, 1 stop bit, LIN Master mode with 13-bit break generation  
LIN_SLAVE_10B 8 data bits, no parity, 1 stop bit, LIN Slave mode with 10-bit break detection  
LIN_SLAVE_11B 8 data bits, no parity, 1 stop bit, LIN Slave mode with 11-bit break detection  
  • Using an I2C or SPI UART like the SC16IS750 is also a good way to add support for other bit length, parity, and stop bit options on Gen 3 devices.

Analog input (ADC)

For analog to digital conversion (ADC) using analogRead(), there are fewer ADC inputs on the E404X:

Pin E Series Pin Name E Series ADC E404X Pin Name E404X ADC
19 WKP / A7 A7 / WKP
20 DAC / A6 A6
21 A5 A5
22 A4 A4
23 A3 A3
24 A2 A2
25 A1 A1
26 A0 A0
28 B5 NC  
29 B4 NC  
30 B3 B3  
31 B2 B2  

If additional ADC ports are needed, an external I2C and SPI ADC can be added to your base board.

PWM (Pulse-width modulation)

The pins that support PWM are different on the E Series and E404X.

Pin E Series Pin Name E Series PWM E404X Pin Name E404X PWM E404X Hardware Timer
16 TX TX PWM2
17 RX RX PWM2
19 WKP / A7 A7 / WKP    
20 DAC / A6   A6 PWM3
21 A5 A5 PWM3
22 A4 A4 PWM3
23 A3   A3 PWM1
30 B3 B3 PWM2
31 B2 B2 PWM2
32 B1 B1    
33 B0 B0    
39 D3 NC    
40 D2 D2 PWM1
41 D1 D1 PWM1
42 D0 D0 PWM1
44 C5 C5 PWM0
45 C4 C4 PWM3
49 C0   C0 PWM1

PWM on the same timer group (such as TIM3 or PWM3) must share the same frequency, but can have different duty cycles.

On the E404X, the following groups are defined. Each group must share the same frequency and resolution, but individual pins in the group can have a different duty cycle. Group 0 is shared with the RGB LED and must use the default resolution of 8 bits (0-255) and frequency of 500 Hz, but can have its own duty cycle.

  • Group 0: C5, RGBB, RGBG, RGBR
  • Group 1: A3, C0, D0, D1, D2
  • Group 2: B2, B3, RX, TX
  • Group 3: A4, A5, A6, C4

Digital to analog converter (DAC)

The E Series supports DAC one A3 and A6 (DAC). There is no DAC on the E404X or Gen 3 devices.

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

Pin E Series Pin Name E Series DAC E404X Pin Name E404X DAC
20 DAC / A6 A6  
23 A3 A3  

WKP (A7)

E Series E404X
Module Pin 30 30
Pin Name WKP WKP
A7 A7
Analog Input
PWM

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

This restriction does not exist on the E404X and Gen 3 devices; any pin except B0 and B1 can be used to wake from all sleep modes, rising or falling.

CAN (Controller Area Network)

The E series supported CAN on pins D1/D2 or C4/C5. There is no CAN on the E404X 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 E404X.
Pin E Series Pin Name E Series CAN E404X Pin Name E404X CAN
40 D2 CAN2_RX D2  
41 D1 CAN2_TX D1  
44 C5 CAN1_RX C5  
45 C4 CAN1_TX C4  

I2S (Sound)

  • The E Series theoretically had I2S sound available on pins D1 and D2, however there has never been support for it in Device OS.
  • I2S is available on Gen 3 devices including the P404X on any GPIO pins using a 3rd-party library.

Interrupts

There are many limitations for interrupts on the E Series (STM32F205). All pins can be used for interrupts on the E404X Gen 3 devices, however you can only attach interrupts to 8 pins at a time.

SWD

Unlike the E Series module, the E404X SWD pins are dedicated and cannot be used for GPIO.

Pin E Series Pin Name E Series SWD E404X Pin Name E404X SWD
35 D7 SWDIO SWDIO SWDIO
36 D6 SWCLK SWDCLK SWCLK
38 D4   SWO SWO

JTAG

The E404X does not support full JTAG. Some pins are shared with SWD; the E404X SWD pins are dedicated and cannot be used for GPIO.

Pin D5 (module pin 37), however, is available for GPIO as it is not NC and not used by SWD.

Pin E Series Pin Name E Series JTAG E404X Pin Name E404X JTAG
35 D7 JTAG TMS SWDIO  
36 D6 JTAG TCK SWDCLK  
37 D5 JTAG TDI D5  
38 D4 JTAG TDO SWO  
39 D3 JTAG RST NC  

USB

The following USB feature differences exist:

USB Feature E Series E404X
Secondary USB serial emulation USBSerial1
USB keyboard emulation
USB mouse emulation

Pin functions removed

The following pins were used on the E Series but are not available on the E404X. You should not connect anything to these pins.

Pin Pin Name Description
10 VDDA Power input for ADC. Normally connected to 3V3. Must always be within 300 mV of 3V3.
11 VBAT Battery for internal real-time clock, backup registers, and SRAM. Supply 1.65VDC to 3.6 VDC at 19 μA..
28 B5 B5 Analog in, GPIO
29 B4 B4 Analog in, GPIO
39 D3 D3 GPIO, SPI1

Pin functions added

No pin functions have been added to previously unused (NC) pins.

Full module pin comparison

E404X Pinout Diagram
E Series Pinout Diagram

Module Pin 1 (VIN)

Unchanged between E Series and E404X
Pin Name VIN
Description Power in 3.9V to 12 VDC.

Module Pin 2 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 3 (VBUS)

Unchanged between E Series and E404X
Pin Name VBUS
Description Connect to VBUS power pin on the USB port

Module Pin 4 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 5 (LIPO)

Unchanged between E Series and E404X
Pin Name LIPO
Description Connect to + pin on the LiPo battery, 3.6V maximum

Module Pin 6 (NC)

Unchanged between E Series and E404X
Pin Name NC
Description Do not connect to anything

Module Pin 7 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 8 (PMID)

E Series E404X
Pin Name PMID PMID
Description Connected to the PMID pin of the PMIC Connected to the PMID pin of the PMIC (may change)

Module Pin 9 (3V3)

Unchanged between E Series and E404X
Pin Name 3V3
Description Regulated 3.3V DC output, maximum load 800 mA. Cannot be used as a power input.

Module Pin 10 (VDDA / NC)

E Series E404X
Pin Name VDDA NC
Description Power input for ADC. Normally connected to 3V3. Must always be within 300 mV of 3V3. Do not connect to anything

Module Pin 11 (VBAT / NC)

E Series E404X
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.. Do not connect to anything

Module Pin 12 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 13 (USBDATA+)

E Series E404X
Pin Name USBDATA+ USBDATA+
Description USB Data+ USB Data+. Cannot be used as GPIO.
Input is 5V Tolerant Yes Yes

Module Pin 14 (USBDATA-)

E Series E404X
Pin Name USBDATA- USBDATA-
Description USB Data- USB Data-. Cannot be used as GPIO.
Input is 5V Tolerant Yes Yes

Module Pin 15 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 16 (TX)

E Series E404X
Pin Name TX TX
Description Serial1 TX (transmitted data), GPIO, PWM. Serial1 TX (transmitted data), GPIO D8, PWM.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
UART serial TX. Use Serial1 object. TX. Use Serial1 object.
Supports attachInterrupt Yes. C3 and TX share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 17 (RX)

E Series E404X
Pin Name RX RX
Description Serial1 RX (received data), GPIO, PWM. Serial1 RX (received data), GPIO D9, PWM.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
UART serial RX. Use Serial1 object. RX. Use Serial1 object.
Supports attachInterrupt Yes. C4 and RX share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes Yes

Module Pin 18 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 19 (WKP / A7)

E Series E404X
Pin Name WKP A7
Pin Alternate Name A7 WKP
Description WKP/A7 Wakeup (active high), analog in, GPIO. A7 analog in, WKP (wakeup), GPIO D17.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone Yes No
Supports attachInterrupt Yes. A7 (WKP), B2, and B4 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 20 (DAC / A6)

E Series E404X
Pin Name DAC A6
Pin Alternate Name A6 n/a
Description DAC/A6 True analog out, analog in, GPIO. A6 analog in, PWM, GPIO D16.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (DAC) Yes No
Supports analogWrite (PWM) No Yes
Supports tone No Yes
Supports attachInterrupt Yes. D3 and DAC/A6 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K

Module Pin 21 (A5)

E Series E404X
Pin Name A5 A5
Description A5 Analog in, GPIO, SPI MOSI. A5 Analog in, GPIO D15, SPI MOSI, 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. MOSI. Use SPI object.
Supports attachInterrupt No Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 22 (A4)

E Series E404X
Pin Name A4 A4
Description A4 Analog in, GPIO, SPI MISO. A4 Analog in, GPIO D14, SPI MISO, PWM.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (PWM) Yes. D3 and A4 share the same PWM channel and the PWM duty cycle is set for both. Yes
Supports tone Yes. D3 and A4 share the same PWM channel and only one frequency can be set for both. Yes
SPI interface MISO. Use SPI object. MISO. Use SPI object.
Supports attachInterrupt Yes. D1 and A4 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 23 (A3)

E Series E404X
Pin Name A3 A3
Description A3 True analog out, analog in, GPIO. A3 analog in, GPIO D13, SPI SCK, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports analogWrite (DAC) Yes No
Supports analogWrite (PWM) No Yes
Supports tone No Yes
SPI interface SCK. Use SPI object. SCK. Use SPI object.
Supports attachInterrupt Yes. D2, A0, and A3 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K

Module Pin 24 (A2)

E Series E404X
Pin Name A2 A2
Description A2 Analog in, GPIO, SPI SS A2 Analog in, GPIO D12, SPI SS
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
SPI interface SS. Use SPI object. This is only the default SS/CS pin, you can use any GPIO instead. SS. Use SPI object. This is only the default SS/CS pin, you can use any GPIO instead.
Supports attachInterrupt Yes. A2 and C0 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 25 (A1)

E Series E404X
Pin Name A1 A1
Description A1 Analog in, GPIO A1 Analog in, GPIO D11
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes Yes
Supports attachInterrupt Yes. D4 and A1 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 26 (A0)

E Series E404X
Pin Name A0 A0
Description A0 Analog in, GPIO A0 Analog in, GPIO D10
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. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 27 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 28 (B5 / NC)

E Series E404X
Pin Name B5 NC
Description B5 Analog in, GPIO Do not connect to anything
Supports digitalRead Yes n/a
Supports digitalWrite Yes n/a
Supports analogRead Yes n/a
Supports attachInterrupt Yes. B3 and B5 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 29 (B4 / NC)

E Series E404X
Pin Name B4 NC
Description B4 Analog in, GPIO Do not connect to anything
Supports digitalRead Yes n/a
Supports digitalWrite Yes n/a
Supports analogRead Yes n/a
Supports attachInterrupt Yes. A7 (WKP), B2, and B4 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 30 (B3)

E Series E404X
Pin Name B3 B3
Description B3, analog in, GPIO, PWM B3, GPIO D21, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
Supports attachInterrupt Yes. B3 and B5 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 31 (B2)

E Series E404X
Pin Name B2 B2
Description B2, analog in, GPIO, PWM B2, GPIO D20, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogRead Yes No
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
Supports attachInterrupt Yes. A7 (WKP), B2, and B4 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 32 (B1)

E Series E404X
Pin Name B1 B1
Description B1, GPIO, PWM B1, GPIO D19
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone Yes No
Supports attachInterrupt Yes. D1, A4, and B1 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 33 (B0)

E Series E404X
Pin Name B0 B0
Description B0, GPIO, PWM B0, GPIO D18
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes No
Supports tone Yes No
Supports attachInterrupt Yes. B0 and C5 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 34 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 35 (D7 / SWDIO)

E Series E404X
Pin Name D7 SWDIO
Description D7 GPIO SWDIO for JTAG/SWD debugger. Internal pull-up. Not GPIO.
Supports digitalRead Yes No
Supports digitalWrite Yes No
Supports attachInterrupt No. Shared with BAT_INT_PC13 No
Internal pull-up or pull-down resistance 40K. Pull-up applied in bootloader for JTAG. n/a
Input is 5V Tolerant Yes No
JTAG interface JTAG TMS. 40K pull-up at boot. n/a
SWD interface SWDIO. 40K pull-up at boot. SWDIO
Signal used at boot JTAG TMS/SWDIO. 40K pull-up at boot. JTAG SWDIO. 40K pull-up at boot.

Module Pin 36 (D6 / SWDCLK)

E Series E404X
Pin Name D6 SWDCLK
Description D6 GPIO SWCLK for JTAG/SWD debugger. Internal pull-down. Not GPIO.
Supports digitalRead Yes No
Supports digitalWrite Yes No
Supports attachInterrupt Yes No
Internal pull-up or pull-down resistance 40K. Pull-up applied in bootloader for JTAG. n/a
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
Signal used at boot JTAG TCK/SWCLK. 40K pull-down at boot. JTAG SWCLK. 40K pull-down at boot.

Module Pin 37 (D5)

E Series E404X
Pin Name D5 D5
Description D5 GPIO, SPI1 D5 GPIO, SPI1 SS
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
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. You can only have 8 active interrupt pins.
I2S interface I2S3_WS n/a
Internal pull-up or pull-down resistance 40K 13K
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 38 (D4 / SWO)

E Series E404X
Pin Name D4 SWO
Description D4 GPIO, SPI1 SWO for JTAG/SWD debugger. Not GPIO.
Supports digitalRead Yes No
Supports digitalWrite Yes No
SPI interface SCK. Use SPI1 object. n/a
Supports attachInterrupt Yes. D4 and A1 share the same interrupt handler. No
I2S interface I2S3_SD n/a
Internal pull-up or pull-down resistance 40K n/a
Input is 5V Tolerant Yes No
JTAG interface JTAG TDO. Floating at boot. n/a
SWD interface n/a SWO
Signal used at boot JTAG TDO. Floating at boot. JTAG SWO.

Module Pin 39 (D3 / NC)

E Series E404X
Pin Name D3 NC
Description D3 GPIO, SPI1 Do not connect to anything
Supports digitalRead Yes n/a
Supports digitalWrite 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 SPI1 object. n/a
Supports attachInterrupt Yes. D3 and DAC/A6 share the same interrupt handler. n/a
Internal pull-up or pull-down resistance 40K. Pull-up applied in bootloader for JTAG. n/a
Input is 5V Tolerant Yes n/a
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 40 (D2)

E Series E404X
Pin Name D2 D2
Description D2 GPIO, SPI1, CAN D2 GPIO, PWM
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. 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 SPI1 object. n/a
Supports attachInterrupt Yes. D2, A0, and A3 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
CAN interface CAN2_RX n/a
I2S interface I2S3_SD n/a
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 41 (D1)

E Series E404X
Pin Name D1 D1
Description D0 GPIO, I2C, CAN D0 GPIO, I2C Wire SCL, Serial1 RTS, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
UART serial n/a CTS flow control (optional). Use Serial1 object.
I2C interface SCL. Use Wire object. Use 1.5K to 10K external pull-up resistor. Is 5V tolerant. SCL. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt Yes. D1, A4, and B1 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
CAN interface CAN2_TX n/a
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 42 (D0)

E Series E404X
Pin Name D0 D0
Description D0 GPIO, I2C D0 GPIO, I2C Wire SDA, Serial1 CTS, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
UART serial n/a RTS flow control (optional). Use Serial1 object.
I2C interface SDA. Use Wire object. Use 1.5K to 10K external pull-up resistor. Is 5V tolerant. SDA. Use Wire object. Use 1.5K to 10K external pull-up resistor.
Supports attachInterrupt No Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 43 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 44 (C5)

E Series E404X
Pin Name C5 C5
Description I2C, CAN, GPIO. GPIO D29, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes Timer is shared with RGB LED; duty cycle can be set but not frequency.
Supports tone Yes No
I2C interface SCL. Use Wire1 object. You can only use Wire or Wire1, not both! n/a
Supports attachInterrupt Yes. B0 and C5 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
CAN interface CAN1_RX n/a
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 45 (C4)

E Series E404X
Pin Name C4 C4
Description I2C, CAN, GPIO. GPIO D28, PWM
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) Yes Yes
Supports tone Yes Yes
I2C interface SDA. Use Wire1 object. You can only use Wire or Wire1, not both! n/a
Supports attachInterrupt Yes. C4 and RX share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
CAN interface CAN1_TX n/a
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 46 (C3)

E Series E404X
Pin Name C3 C3
Description Serial4 TX (transmitted data), SPI2, GPIO. SPI1 SCK, GPIO D27.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial TX. Use Serial4 object. n/a
SPI interface SCK. Use SPI2 object. SCK. Use SPI1 object.
Supports attachInterrupt Yes. C3 and TX share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 47 (C2)

E Series E404X
Pin Name C2 C2
Description Serial4 RX (received data), SPI2, GPIO. SPI1 MISO, GPIO D26.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial RX. Use Serial4 object. n/a
SPI interface MISO. Use SPI2 object. MISO. Use SPI1 object.
Supports attachInterrupt No Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 48 (C1)

E Series E404X
Pin Name C1 C1
Description Serial5 TX (trasmitted data), SPI2, GPIO. SPI1 MOSI, GPIO D25.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
UART serial TX. Use Serial5 object. n/a
SPI interface MOSI. Use SPI2 object. MOSI. Use SPI1 object.
Supports attachInterrupt No Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 49 (C0)

E Series E404X
Pin Name C0 C0
Description Serial5 RX (received data), GPIO. GPIO D24, PWM.
Supports digitalRead Yes Yes
Supports digitalWrite Yes Yes
Supports analogWrite (PWM) No Yes
Supports tone No Yes
UART serial RX. Use Serial5 object. n/a
Supports attachInterrupt Yes. A2 and C0 share the same interrupt handler. Yes. You can only have 8 active interrupt pins.
Internal pull-up or pull-down resistance 40K 13K
Input is 5V Tolerant Yes No

Module Pin 50 (NC)

Unchanged between E Series and E404X
Pin Name NC
Description Do not connect to anything

Module Pin 51 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 52 (RGBB)

E Series E404X
Pin Name RGBB RGBB
Description RGB LED Blue RGB LED Blue
UART serial RX. Use Serial2 object. n/a

Module Pin 53 (RGBG)

E Series E404X
Pin Name RGBG RGBG
Description RGB LED Green RGB LED Green
UART serial TX. Use Serial2 object. n/a

Module Pin 54 (RGBR)

Unchanged between E Series and E404X
Pin Name RGBR
Description RGB LED Red

Module Pin 55 (MODE)

E Series E404X
Pin Name MODE MODE
Description MODE button, has internal pull-up. Pin number constant is BTN. MODE button, has internal pull-up. Pin number constant is BTN.
I2S interface I2S3_MCK n/a

Module Pin 56 (RESET)

Unchanged between E Series and E404X
Pin Name RESET
Description Hardware reset. Pull low to reset; can leave unconnected in normal operation.

Module Pin 57 (STAT)

Unchanged between E Series and E404X
Pin Name STAT
Description Charge status output from the PMIC.

Module Pin 58 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 59 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Module Pin 60 (GND)

Unchanged between E Series and E404X
Pin Name GND
Description Ground. Be sure to connect all GND pins.

Software

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

Since the E404X uses the same MCU as Gen 3 devices (Boron, B Series SoM, Tracker SoM), most libraries intended for those platforms will work with no changes or minimal changes.

Version History

Revision Date Author Comments
pre 2022-01-25 RK Pre-release
2022-03-14 RK Minor edits; no functional changes
2022-05-06 RK Wire1 is not exposed on C4/C5
2022-07-28 RK Update PWM assignments
2022-09-12 RK Added notes about I2C pull-ups and leakage current