Wire-free Miniscope v4
The wire-free Miniscope v4 is a battery powered, data logging Miniscope based around the original wired Miniscope v4 project. All code, CAD, and PCB files can be found at https://github.com/Aharoni-Lab/Miniscope-v4-Wire-Free
Specifications
- Weight:
- Size:
- Field of View:
- Recording Resolution:
- Recording Length:
- Record Triggering:
Overview of System
Workflow of Recording
Extracting Data from SD Card
MCU Firmware Walkthrough
The microcontroller (MCU) used in the Wire-Free Miniscope v4 is an ATSAMD51. It sits between the Python 480 CMOS image sensor and the micro SD Card and handles all on-board control and operation of the Miniscope. The firmware uses a combination of custom written driver and ones imported using ATMEL SMART.
Initialization
State Machine
// ---------- Device State Definitions -------
#define DEVICE_STATE_IDLE 1<<1
#define DEVICE_STATE_START_RECORDING 1<<2
#define DEVICE_STATE_RECORDING 1<<3
#define DEVICE_STATE_STOP_RECORDING 1<<4
#define DEVICE_STATE_CHARGING 1<<5
#define DEVICE_STATE_CONFIG_LOADED 1<<6
#define DEVICE_STATE_ERROR 1<<7
#define DEVICE_STATE_LOW_VOLTAGE 1<<8
#define DEVICE_STATE_START_RECORDING_WAITING 1<<9
#define DEVICE_STATE_SDCARD_WRITE_ERROR 1<<10
#define DEVICE_STATE_SDCARD_INIT_WRITE_ERROR 1<<11
Once the MCU moves into the device = DEVICE_STATE_RECORDING, management of detecting newly filled buffers and sending those over to the SD Card is all handed within the function void recording().
DMA
The MCU using Direct Memory Access (DMA) to stream pixel data into memory from the image sensor as well as write imaging data from memory into the SD Card. For pixel data coming from the image sensor, the MCU uses its Parallel Capture Controller (PCC) with DMA to handle an 8-bit parallel pixel bus. For writing imaging data into the SD Card, the MCU uses its ADMA to move raw data in the MCU memory into the SD Card storage blocks.
PCC DMA (Image Sensor -> MCU Memory)
SD Card ADMA (MCU Memory -> SD Card)
Writing and reading from the SD Card takes advantage of ADMA. I can't quite remember what all the differences are here between ADMA and regular DMA but it took a while to get up and running. To get everything up and running in the firmware, I added two additional functions in sd_mmc.c:
- sd_mmc_err_t sd_mmc_write_with_ADMA(uint8_t slot, uint32_t start, uint32_t *descAdd, uint16_t nb_block)
- sd_mmc_err_t sd_mmc_wait_end_of_ADMA_write(bool abort)