Set I2C Protocol between Pi & ESP32

[bgoodwine]

Protocol Draft 1

Pi initial requests:

• 0: = request for general checkin
• 1:[IMU data] = IMU data that the ESP32 should either confirm or alert mismatching data
• 2:[num_bytes] = transmit message via SDR
• 3:sensor_id = restart sensor corresponding to sensor_id
• 4:sensor_id = shutdown sensor corresponding to sensor_id
• 0:2 = start relay of available SDR message (sent after receiving 0:2 from ESP32)
• 0:3 = start relay of solar panel efficiency report (sent after receiving 0:3 from ESP32)

ESP32 response to general checkin:

• 0:0 = not tumbling
• 0:1 = tumbling alert
• 0:2:[num_bytes] = message from SDR waiting to be relayed
• 0:3:[num_bytes] = solar panel efficiency report available for relay

ESP32 response to IMU data:

• 1:0 = IMU data is good
• 1:1 = IMU data does not match
• 1:report:[solar panel report] = solar panel efficiency report
• 2:num_bytes = number of bytes in message received from the SDR, which the ESP32 will next relay to the Pi
• 2:[message] = message relayed to Pi, will only be num_bytes long

ESP32 data relay:

• 2:[message] - SDR message to relay, repeat until num_bytes has been sent (-2 for each sent message)
• 3:[report] - solar panel efficiency report to relay, repeat until num_bytes has been sent (-2 for each sent message)

Originally posted by @bgoodwine in https://github.com/bgoodwine/SeniorDesign/issues/2#issuecomment-1438757839

[bgoodwine]

TODO

• [ ] Change structure of i2c_esp32.py to be functions for import in other programs
• [ ] Add functions for each type of message to send (checkin(), send_to_sdr(message), send_imu_update(imu_data), etc.)
• [ ] Send opcode and num_bytes for all messages
• [ ] Repeat messages in 32-byte chunks until whole message sent
• [ ] Add receiving message components function to ESP32 program (BEFORE case statement... put data as ONE string)
• [ ] Flesh out ESP32 opcode functions (?)

[bgoodwine]

Protocol Draft 2

Pi initial messages:

• 0: - general checking request
• 1:sensor_id - restart sensor corresponding to sensor_id
• 2:sensor_id - shutdown sensor corresponding to sensor_id
• 3:[num_bytes] - misc. message from Pi to ESP32

Pi responses to message transmission requests:

• 0:2 - start relay of message to be sent to SDR (after receiving 0:2:[num_bytes] from ESP32)
• 0:3 - start relay of solar panel efficiency report (sent after receiving 0:3:[num_bytes] from ESP32)
• 0:4 - start relay of misc. message from ESP32 (sent after receiving 0:4:[num_bytes] from ESP32)

ESP32 response to general checkin:

• 0:0 - not tumbling
• 0:1 - tumbling alert
• 0:2:[num_bytes] - a message of num_bytes bytes is waiting to be relayed to the Pi for transmission through the SDR
• 0:3:[num_bytes] - solar panel efficiency report of num_bytes bytes is waiting to be relayed to the Pi
• 0:4:[num_bytes] - misc. message available for relay from ESP32 to Pi

ESP32 response to restart/shutdown commands:

• 1:0:[sensor_id] - successfully restarted sensor of sensor_id
• 1:1:[sensor_id] - failed to restart sensor of sensor_id
• 2:0:[sensor_id] - successfully shutdown sensor of sensor_id
• 2:1:[sensor_id] - failed to shutdown sensor of sensor_id

ESP32 data relay messages will be repeated until all bytes have been transmitted:

• 0:2:[message] - packetized data for transmission through SDR
• 0:3:[message] - solar panel efficiency report
• 0:4:[message] - misc. message from ESP32 to Pi Note: the preceding opcode and delimiter will be included in the num_bytes originally sent.

[bgoodwine]

Send I2C data back from ESP32 S3

Read byte at a time with smbus

read_byte(i2c_addr, force=None)
Read a single byte from a device.
Return type int
Parameters
• i2c_addr (int) – i2c address
• force (Boolean) –
Returns Read byte value

uint8 data type in python read block data

[bgoodwine]

TODO

Lots of functionality added with #13 closed :) What's still left:

• Make checkin() a request from function
• Have Pi call the get functions based off of response from checkin
• Send variable lengths messages !