Arducam Mega — STM32F429 Extension

This folder contains examples that extend the Arducam_Mega library for use on the STM32F429 (tested on NUCLEO-F429ZI). The standard library targets generic Arduino boards; these examples add the pin configuration and helper classes needed to run correctly on STM32F429.

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Why an extension is needed

The Arducam_Mega library selects its hardware abstraction layer (HAL) at compile time via src/Arducam/Platform.h. When compiling for STM32F4xx under the Arduino core (STM32F4xx && ARDUINO is defined), it automatically picks ArduinoHal.h, which maps SPI and delay calls to the Arduino API. That part works without changes.

What the generic library does not configure is:

Problem	Solution in these examples
STM32F429 NUCLEO default SPI1 pins conflict with other on-board peripherals	Explicitly remap SPI1 to alternate pins PB3/PB4/PB5 before calling myCAM.begin()
ST-Link virtual COM port uses USART3 (PD8/PD9), not the default Serial pins	ArducamLink calls Serial.setTx(PD_8) / Serial.setRx(PD_9) before Serial.begin()
Arduino-style integer pin numbers (e.g. 7) do not map to the correct STM32 ports	All CS pins use STM32 port notation (PE_7, PB_12, etc.)

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Shared SPI setup

Both examples configure SPI1 the same way in setup():

SPI.setMISO(PB_4);
SPI.setMOSI(PB_5);
SPI.setSCLK(PB_3);
SPI.begin();

This must be done before myCAM.begin(), because begin() internally calls SPI.begin() and will use whichever pins are currently configured.

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Examples

full_featured

Streams camera data over UART to the Arducam Android/PC host app. Supports all camera controls: resolution, format, brightness, contrast, white balance, exposure, gain, focus, special effects, and streaming.

Extra files in this example:

• ArducamUart.h — thin macros that map SerialBegin, SerialWrite, etc. to the Arduino Serial object.
• ArducamLink.h / ArducamLink.cpp — command parser and UART framing layer. Receives binary command packets from the host app, calls the corresponding Arducam_Mega API, and sends framed responses back.

Pin assignment:

Signal	STM32 Pin
SPI1 SCK	PB3
SPI1 MISO	PB4
SPI1 MOSI	PB5
Camera CS	PE7
UART TX (USART3)	PD8
UART RX (USART3)	PD9

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capture2SD

Captures a JPEG photo every 5 seconds and saves it as a numbered file (0.jpg, 1.jpg, …) on a FAT-formatted SD card.

The SD card module shares SPI1 with the camera — this is normal SPI bus behaviour; each device is deselected (CS high) when not in use. The standard Arduino SD library is used, which only supports the default SPI object.

Pin assignment:

Signal	STM32 Pin
SPI1 SCK	PB3
SPI1 MISO	PB4
SPI1 MOSI	PB5
Camera CS	PE7
SD card CS	PB12 (change SD_CS to match your wiring)
UART TX (USART3)	PD8
UART RX (USART3)	PD9

SD card on a separate SPI bus? The Arduino SD library does not support custom SPI instances. Install the SdFat library (Arduino Library Manager) and replace SD.begin(SD_CS) with:

SPIClass SPI_SD(PB_15, PB_14, PB_13); // MOSI, MISO, SCK (SPI2)
SdFat SD;
SD.begin(SdSpiConfig(SD_CS, DEDICATED_SPI, SD_SCK_MHZ(25), &SPI_SD));

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Known issues and fixes

Linker error: undefined reference to arducamSpiCsPinLow / arducamSpiCsPinHigh / arducamCsOutputMode

Symptom — compilation fails at the link stage with errors like:

ArducamCamera.c:(.text.cameraCsLow+0x2): undefined reference to `arducamSpiCsPinLow'
ArducamCamera.c:(.text.cameraCsHigh+0x2): undefined reference to `arducamSpiCsPinHigh'
ArducamCamera.c:(.text.cameraInit+0xa): undefined reference to `arducamCsOutputMode'

Root cause — arducamSpiCsPinLow, arducamSpiCsPinHigh, and arducamCsOutputMode are not real functions. They are macros defined in src/Arducam/ArduinoHal.h that alias them to the actual SPI helpers:

#define arducamSpiCsPinHigh(pin)  arducamSpiCsHigh(pin)
#define arducamSpiCsPinLow(pin)   arducamSpiCsLow(pin)
#define arducamCsOutputMode(pin)  arducamSpiCsOutputMode(pin)

src/Arducam/Platform.h selects which HAL header to include based on preprocessor macros. The STMicroelectronics Arduino core defines ARDUINO_ARCH_STM32, but the upstream library only checked for STM32F7xx && ARDUINO, so no HAL was included and the macros were never defined.

Fix — add ARDUINO_ARCH_STM32 to the condition in src/Arducam/Platform.h:

// Before
#elif defined(__AVR__) || ... || (defined(STM32F7xx) && defined(ARDUINO))

// After
#elif defined(__AVR__) || ... || (defined(STM32F7xx) && defined(ARDUINO)) || defined(ARDUINO_ARCH_STM32)

This change has been applied to this copy of the library. If you update the library via the Arduino Library Manager, re-apply this one-line change to src/Arducam/Platform.h.

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Dependencies

Library	Where to get
Arducam_Mega	github.com/ArduCAM/Arducam_Mega
SD (built-in)	Arduino Library Manager — included with Arduino IDE
STM32 Arduino core	github.com/stm32duino/Arduino_Core_STM32

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Board selection in Arduino IDE

1. Install the STM32 core via Boards Manager (search STM32).
2. Select STM32 boards (selected from submenu) → Nucleo-144 → Nucleo F429ZI.
3. Under Tools → USB support, select CDC (generic Serial supersede U(S)ART) if you want USB serial; otherwise use the ST-Link virtual COM port (PD8/PD9).