- STM32F401RETx (e.g., Nucleo F401RE)
- STM32F401CCUx (e.g., STM32F401CCU6 WeAct 3.0 Black Pill)
- STM32F411CEUx (e.g., STM32F411CEU6 WeAct 2.0 Black Pill)
this is firmware for STM32F401RETx microcontrollers that reads pixel data from the TCD1304AP linear CCD sensor and transmits it in realtime over UART
there is an included ccdview.py which visualises this data
(sensor was a bit dirty during this)
this is an STM32CubeIDE project and uses the STM32F4xx hardware abstraction layer
| signal | device | stm32 pin | dev board pin | comments |
|---|---|---|---|---|
| fM | TIM3-CH3 | PB0 | A3 | to 74HC04 |
| SH | TIM2-CH2 | PA1 | A1 | to 74HC04 |
| ICG | TIM5-CH1 | PA0 | A0 | to 74HC04 |
| DATA | TIM4-CH4 | PB9 | D14 | triggers the ADC -- only for debug |
| OS | ADC1 | PC0 | A5 | input from OS line |
| TX | USART1 | PA9 | D8 | to PC running ccdview.py |
| RX | USART1 | PA10 | D2 | not currently used |
PC13 or the B1 button on the NUCLEO F401RE board will start/stop the image acquisition
in Core/Src/main.c you will find
volatile uint8_t exposure = 20;
you can calculate the exposure time like so exposure*3.7ms = total exposure time
the minimum exposure value for a 2MHz fM is 2, or 7.388ms
volatile uint8_t avg = 1;
setting this value to >1 will average multiple exposures before sending the data over USART1
note: sending the 3694 pixels over USART1 at 500000 baud takes ~150ms, so if your total exposure time is much less than this, you might as well average a couple exposures before sending them
Core/Inc/consts.h contains the following constants
| constant | value | description |
|---|---|---|
| CPU_freq | 84000000 | the frequency of your STM32 chip |
| CCD_freq | 2000000 | the master clock frequency (fM) |
| NUM_PIXELS | 3694 | number of pixels on the CCD |
| BAUD_RATE | 500000 | the USART1 baud rate |
you can launch the realtime visualisation script like so:
python3 ccdview.py <DEVICE> <BAUD RATE>
python3 ccdview.py /dev/ttyUSB0 500000