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Fully implementation library support OV2640 camera on STM32 platform

POC

🚀 Features

Support for resolutions:

  • 160X120px,
  • 320X240px,
  • 640X480px,
  • 800x600px,
  • 1024x768px,
  • 1280x960px,

Added support for extra special effects:

  • brightness,
  • saturation,
  • contrast,
  • light mode,
  • special effect such as: antique, bluish, greenish, reddish, black & white style, negative, Negative with black & white style and normal view.

Support for libjpeg library. Branch with example: https://github.com/SimpleMethod/STM32-OV2640/tree/Imageoptimization

Code optimization, now requires 10 times less space in buffer than before!

📚 Documentation

The maximum size of the data buffer is 65535 bytes and this is also the maximum size of a single DCMI read. For higher resolutions, you must use the circular buffer and write own implementation in HAL_DCMI_IRQHandler. XCLX is actually the clock output from the MCU (RCC_MCO_1). The minimum speed is around 27MHz, but as high as possible is recommended for correct functioning.

Pin configuration:

PERIPHERALS MODES FUNCTIONS PINS
DCMI Slave 8 bits External Synchro DCMI_D0 PC6
DCMI Slave 8 bits External Synchro DCMI_D1 PC7
DCMI Slave 8 bits External Synchro DCMI_D2 PC8
DCMI Slave 8 bits External Synchro DCMI_D3 PC9
DCMI Slave 8 bits External Synchro DCMI_D4 PE4
DCMI Slave 8 bits External Synchro DCMI_D5 PD3
DCMI Slave 8 bits External Synchro DCMI_D6 PE5
DCMI Slave 8 bits External Synchro DCMI_D7 PE6
DCMI Slave 8 bits External Synchro DCMI_HSYNC PA4
DCMI Slave 8 bits External Synchro DCMI_PIXCLK PA6
DCMI Slave 8 bits External Synchro DCMI_VSYNC PG9
I2C1 I2C I2C1_SCL PB8
I2C1 I2C I2C1_SDA PB9
RCC BYPASS Clock Source RCC_OSC_IN PH0/OSC_IN
RCC BYPASS Clock Source RCC_OSC_OUT PH1/OSC_OUT
RCC Crystal/Ceramic Resonator RCC_OSC32_IN PC14/OSC32_IN
RCC Crystal/Ceramic Resonator RCC_OSC32_OUT PC15/OSC32_OUT
RCC Clock-out-1 RCC_MCO_1 (DCMI_XCLX) PA8
SYS Serial Wire SYS_JTCK-SWCLK PA14
SYS Serial Wire SYS_JTMS-SWDIO PA13
SYS SysTick SYS_VS_Systick VP_SYS_VS_Systick
USART3 Asynchronous USART3_RX PD9
USART3 Asynchronous USART3_TX PD8
GPIO Output CAMERA_RESET PG0
GPIO Output CAMERA_PWDN PG1
GPIO EXTI13 USER_Btn PC13

DCMI configuration:

OPTION VALUE
Pixel clock polarity Active on Rising edge
Vertical synchronization polarity Active Low
Horizontal synchronization polarity Active Low
Frequency of frame capture All frames are captured
JPEG mode Enabled

I2C configuration:

I2C Speed Mode Standard Mode
I2C Speed Frequency (KHz) 100
Rise Time (ns) 0
Fall Time (ns) 0
Coefficient of Digital Filter 0
Analog Filter 0
Timing 0x1060669A
Clock No Stretch Mode Disabled
General Call Address Detection Disabled
Primary Address Length selection 7-bit
Primary slave address 0

USART configuration:

OPTION VALUE
Baud Rate 115200
Word Length 8 Bits(including Parity)
Parity None
Stop Bits 1
Coefficient of Digital Filter 0
Data Direction Receive and Transmit
Over Sampling 16 Samples
Single Sample Disable
Auto Baudrate Disable
TX Pin Active Level Inversion Disable
RX Pin Active Level Inversion Disable
Data Inversion Disable
TX and RX Pins Swapping
Overrun Enable
DMA on RX Error Enable
MSB First Disable

DMA configuration:

DMA request Stream Direction Priority
DCMI DMA2_Stream1 PeripheralTo Memory Very High
USART3_TX DMA1_Stream3 Memory To Peripheral Very High

DMA2_Stream1 DMA request settings:

OPTION VALUE
Mode Circular
Use fifo Enable
FIFO Threshold Full
Peripheral Increment Disable
Memory Increment Enable
Peripheral Data Width Word
Memory Data Width Byte
Peripheral Burst Size Single
Memory Burst Size Single

DMA1_Stream3 DMA request settings

OPTION VALUE
Mode Normal
Use fifo Enable
FIFO Threshold Full
Peripheral Increment Disable
Memory Increment Enable
Peripheral Data Width Byte
Memory Data Width Byte
Peripheral Burst Size Single
Memory Burst Size Single

NVIC configuration

Interrupt Table Enable Preenmption Priority SubPriority
Non maskable interrupt true 0 0
Hard fault interrupt true 0 0
Memory management fault true 0 0
Pre-fetch fault, memory access fault true 0 0
Undefined instruction or illegal state true 0 0
System service call via SWI instruction true 0 0
Debug monitor true 0 0
Pendable request for system service true 0 0
System tick timer true 0 0
DMA1 stream3 global interrupt true 0 0
USART3 global interrupt true 0 0
DMA2 stream1 global interrupt true 0 0
DCMI global interrupt true 0 0
PVD interrupt through EXTI line 16 unused
Flash global interrupt unused
RCC global interrupt unused
I2C1 event interrupt unused
I2C1 error interrupt unused
EXTI line[15:10]interrupts unused
FPU global interrupt unused

📚 Example use

1. Receive the data using a terminal or other software, default speed is set to 115200 baud.

2. Save the data dump to a file.

3. Open the file and search for the beginning of the JPEG header, it must be FFF8 value.

Open file and serach header

4. In the opened file search for the end of the data, this must be FFD9 value.

Serach footer of jpeg file

5. Open the hexadecimal editor. The example uses https://hexed.it/ and copy the data from the data dump.

Copy data from data dump to hexadecimal editor

6. Our data must start with FFD8 and end with FFD9.

JPEG header JPEG footer

7. Save and open the newly created file.

enter image description here

8. Now it's all depending on you.

Example image #1 Example image #2 Example image #3

💀 My code doesn't work, nothing happens, what to do?

You need to make sure that:

  1. Using short connection wires , less than 10 cm (3.93 inches) - This is very, very, very important!,
  2. All wires are properly connected,
  3. Have a high enough clock speed for the MCU,

Use 320x240px resolution for testing - it always works :-)