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Pycom GPy
ESP32 board with LTE CAT-M1/NB-IoT and Wi-Fi - designed for low-power cellular IoT applications.
55 × 20 mm
ESP32
MCU
240MHz
clock
8MB
flash
520KB
SRAM
27· 18 ADC
GPIO
BLE 4.2+ WiFi
radio
Pinout
27 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | LED_BUILTINA11T1 | strapping | adc · touch | |
| 2 | 1 | TXPWM | uart | uart | |
| 3 | 2 | A12T2PWM | strapping | adc · touch | |
| 4 | 3 | RXPWM | uart | uart | |
| 5 | 4 | A10T0PWM | strapping | adc · touch | |
| 6 | 5 | LTE_TXPWM | strapping | - | |
| 7 | 12 | SDAA15T5PWM | strapping | adc · touch · i2c | |
| 8 | 13 | SCLSCKA14T4PWM | strapping | adc · touch · spi · i2c | |
| 9 | 14 | A16T6PWM | strapping | adc · touch | |
| 10 | 15 | A13T3PWM | strapping | adc · touch | |
| 11 | 17 | SSPWM | strapping | spi | |
| 12 | 18 | LTE_CTSPWM | safe | - | |
| 13 | 19 | LTE_RTSPWM | safe | - | |
| 14 | 21 | ANT_SELECTPWM | safe | - | |
| 15 | 22 | MOSIPWM | safe | spi | |
| 16 | 23 | LTE_RXPWM | safe | - | |
| 17 | 25 | A18DAC1PWM | safe | adc · dac | |
| 18 | 26 | A19DAC2PWM | safe | adc · dac | |
| 19 | 27 | LTE_WAKEA17T7PWM | safe | adc · touch | |
| 20 | 32 | A4T9PWM | safe | adc · touch | |
| 21 | 33 | A5T8PWM | safe | adc · touch | |
| 22 | 34 | A6 | strapping | adc | |
| 23 | 35 | A7 | strapping | adc | |
| 24 | 36 | A0 | strapping | adc | |
| 25 | 37 | MISOA1 | strapping | adc · spi | |
| 26 | 38 | A2 | strapping | adc | |
| 27 | 39 | A3 | strapping | adc |
Start with these
10 pins with no boot or system involvementLTE_CTSPWMLTE_RTSPWMANT_SELECTPWMMOSIPWMLTE_RXPWMA18DAC1A19DAC2LTE_WAKEA17A4T9A5T8
Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| LED_BUILTIN | GPIO0 | Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode. | Strapping |
| A12 | GPIO2 | If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure. | Strapping |
| A10 | GPIO4 | Sampled at reset for boot config; should not be driven at boot (affects boot mode timing). | Strapping |
| LTE_TX | GPIO5 | Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot. | Strapping |
| SDA | MTDI (GPIO12) | Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used. | Strapping |
| SCL | MTCK (GPIO13) | Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed. | Other |
| A16 | MTMS (GPIO14) | Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot. | Other |
| A13 | MTDO (GPIO15) | Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change. | Strapping |
| A6 | GPIO34 | Cannot be used as output (no drive capability); only suitable for analog/digital input. | Other |
| A7 | GPIO35 | Cannot be used as output; only suitable for input. | Other |
| A0 | GPIO36 (SENSOR_VP) | Cannot be used as output; only suitable for input (e.g., analog read). | Other |
| MISO | GPIO37 (SENSOR_CAPP) | Cannot be used as output; only suitable for input. | Other |
| A2 | GPIO38 (SENSOR_CAPN) | Cannot be used as output; only suitable for input. | Other |
| A3 | GPIO39 (SENSOR_VN) | Cannot be used as output; only suitable for input. | Other |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| TX | U0TXD (GPIO1) | Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console. | USB |
| RX | U0RXD (GPIO3) | Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads. | USB |
| SS | GPIO17 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.
Pinout notes The Pycom GPy pinout brings out 27 GPIO pins - every one of them usable in your project. For peripherals, I²C is mapped to SDA on GPIO12 and SCL on GPIO13; the…
The Pycom GPy pinout brings out 27 GPIO pins - every one of them usable in your project.
For peripherals, I²C is mapped to SDA on GPIO12 and SCL on GPIO13; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.
On the analog side there are 18 ADC-capable pins for sensors and battery monitoring, 10 capacitive-touch inputs and 2 true DAC outputs.
If you want zero surprises, LTE_CTS, LTE_RTS, ANT_SELECT, MOSI and 6 more are free of any such role - the safest first picks. 14 of the exposed pins carry boot-time or system duties on the ESP32 (LED_BUILTIN, A12, A10 and 11 more).
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Serial chip: onboard. Not detected? Hold BOOT while plugging in.
2
Flash with your tool
Arduino IDE, PlatformIO, ESPHome or esptool - copy the settings on the right.
3
Verify it runs
The blink example uses GPIO18 - swap for your board's LED pin if different.
Board: Pycom Gpy
Flash Size: 8MB · DIO
Upload Speed: 921600
// blink
pinMode(18, OUTPUT);
digitalWrite(18, LOW); // on (often inverted)[env:gpy]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32dev
variant: gpy
framework:
type: esp-idf
# blink - GPIO18
output:
- platform: gpio
pin: 18
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binBuild details: sketch space 1310720 B · data 327680 B · DIO
Specifications
ESP32 · 55 × 20 mmCompute
MCU
ESP32
Clock
240 MHz
SRAM · Flash
520 KB · 8MB · 4MB (QSPI) PSRAM
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
4.2 LE
Antenna
u.FL
I/O
GPIO · ADC
27 · 18
UART · I²C · SPI
3 · 2 · 4
PWM
16 channels
Power
USB
None
Serial
-
Boot address
0x1000
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · DIO
Sketch · Data
1.25 MB · 320 KB
55 × 20 mm
The Pycom GPy uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with DIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.
About this board
At its core is the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.
Expect to pay about $54.95 - above the ~$20 typical for ESP32 boards.
Onboard you'll find 4MB (QSPI) PSRAM and cellular connectivity (Sequans Monarch LTE-M/NB-IoT).
- Triple-network module: LTE-M/NB-IoT (Sequans Monarch), Wi-Fi & BLE
- Onboard ceramic antenna for Wi-Fi/BLE; u.FL connector for the LTE-M/NB-IoT antenna
- No onboard USB - needs Pycom Expansion Board, Pysense or Pytrack to connect
Where to buy
prices are typical street pricesPycom GPy
$54.95per unit, typical
Resources
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