# Firmware for the Sinara 8451 Thermostat - [x] [Continuous Integration](https://nixbld.m-labs.hk/job/stm32/stm32/thermostat) - [x] [Download latest firmware build](https://nixbld.m-labs.hk/job/stm32/stm32/thermostat/latest/download-by-type/file/binary-dist) ## Building ### Debian-based systems (tested on Ubuntu 19.10) - install git, clone this repository - install [rustup](https://rustup.rs/) ```shell rustup toolchain install nightly rustup update rustup target add thumbv7em-none-eabihf --toolchain nightly rustup default nightly cargo build --release ``` The resulting ELF file will be located under `target/thumbv7em-none-eabihf/release/thermostat` ## Debugging Connect SWDIO/SWCLK/RST/GND to a programmer such as ST-Link v2.1. Run OpenOCD: ```shell openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg ``` You may need to power up the programmer before powering the device. Leave OpenOCD running. Run the GNU debugger: ```shell gdb target/thumbv7em-none-eabihf/release/thermostat (gdb) source openocd.gdb ``` ## Flashing ```shell openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg -c "program target/thumbv7em-none-eabihf/release/thermostat verify reset;exit" ``` ## Network ### Connecting Ethernet, IP: 192.168.1.26/24 Use netcat to connect to port 23/tcp (telnet) ```sh nc -vv 192.168.1.26 23 ``` telnet clients send binary data after connect. Enter \n once to invalidate the first line of input. ### Reading ADC input Set report mode to `on` for a continuous stream of input data. The scope of this setting is per TCP session. ### Commands | Syntax | Function | | --- | --- | | `report` | Show current input | | `report mode` | Show current report mode | | `report mode ` | Set report mode | | `pwm` | Show current PWM settings | | `pwm <0/1> max_i_pos ` | Set PWM duty cycle for **max_i_pos** to *ampere* | | `pwm <0/1> max_i_neg ` | Set PWM duty cycle for **max_i_neg** to *ampere* | | `pwm <0/1> max_v ` | Set PWM duty cycle for **max_v** to *volt* | | `pwm <0/1> ` | Disengage PID, set **i_set** DAC to *ampere* | | `pwm <0/1> pid` | Set PWM to be controlled by PID | | `center <0/1> ` | Set the MAX1968 0A-centerpoint to *volts* | | `center <0/1> vref` | Set the MAX1968 0A-centerpoint to measure from VREF | | `pid` | Show PID configuration | | `pid <0/1> target ` | Set the PID controller target | | `pid <0/1> kp ` | Set proportional gain | | `pid <0/1> ki ` | Set integral gain | | `pid <0/1> kd ` | Set differential gain | | `pid <0/1> output_min ` | Set mininum output | | `pid <0/1> output_max ` | Set maximum output | | `pid <0/1> integral_min ` | Set integral lower bound | | `pid <0/1> integral_max ` | Set integral upper bound | | `s-h` | Show Steinhart-Hart equation parameters | | `s-h <0/1> ` | Set Steinhart-Hart parameter for a channel | | `postfilter` | Show postfilter settings | | `postfilter <0/1> off` | Disable postfilter | | `postfilter <0/1> rate ` | Set postfilter output data rate | | `load` | Restore configuration from EEPROM | | `save` | Save configuration to EEPROM | | `reset` | Reset the device | | `ipv4 ` | Configure IPv4 address | ## USB The firmware includes experimental support for acting as a USB-Serial peripheral. Debug logging will be sent there by default (unless build with logging via semihosting.) **Caveat:** This logging does not flush its output. Doing so would hang indefinitely if the output is not read by the USB host. Therefore output will be truncated when USB buffers are full. ## Temperature measurement Connect the thermistor with the SENS pins of the device. Temperature-depending resistance is measured by the AD7172 ADC. To prepare conversion to a temperature, set the Beta parameters for the Steinhart-Hart equation. Set the base temperature in degrees celsius for the channel 0 thermistor: ``` s-h 0 t0 20 ``` Set the resistance in Ohms measured at the base temperature t0: ``` s-h 0 r0 10000 ``` Set the Beta parameter: ``` s-h 0 b 3800 ``` ## Thermo-Electric Cooling (TEC) - Connect Peltier device 0 to TEC0- and TEC0+. - Connect Peliter device 1 to TEC1- and TEC1+. - The GND pin is for shielding not for sinking Peltier currents. ### Limits Each of the MAX1968 TEC driver has analog/PWM inputs for setting output limits. Use the `pwm` command to see current settings and maximum values. | Limit | Unit | Description | | --- | :---: | --- | | `max_v` | Volts | Maximum voltage | | `max_i_pos` | Amperes | Maximum positive current | | `max_i_neg` | Amperes | Maximum negative current | | | Amperes | Output current control | Example: set the maximum voltage of channel 0 to 1.5 V. ``` pwm 0 max_v 1.5 ``` ### Open-loop mode To manually control TEC output current, omit the limit parameter of the `pwm` command. Doing so will disengage the PID control for that channel. Example: set output current of channel 0 to 0 A. ``` pwm 0 0 ``` ## PID-stabilized temperature control Set the target temperature of channel 0 to 20 degrees celsius: ``` pid 0 target 20 ``` Enter closed-loop mode by switching control of the TEC output current of channel 0 to the PID algorithm: ``` pwm 0 pid ``` ## LED indicators | Name | Color | Meaning | | --- | :---: | --- | | L1 | Red | Firmware initializing | | L3 | Green | Closed-loop mode (PID engaged) | | L4 | Green | Firmware busy | ## Reports Use the bare `report` command to obtain a single report. Enable continuous reporting with `report mode on`. Reports are JSON objects with the following keys. | Key | Unit | Description | | --- | :---: | --- | | `channel` | Integer | Channel `0`, or `1` | | `time` | Milliseconds | Temperature measurement time | | `adc` | Volts | AD7172 input | | `sens` | Ohms | Thermistor resistance derived from `adc` | | `temperature` | Degrees Celsius | Steinhart-Hart conversion result derived from `sens` | | `pid_engaged` | Boolean | `true` if in closed-loop mode | | `i_set` | Amperes | TEC output current | | `vref` | Volts | MAX1968 VREF (1.5 V) | | `dac_value` | Volts | AD5680 output derived from `i_set` | | `dac_feedback` | Volts | ADC measurement of the AD5680 output | | `i_tec` | Volts | MAX1968 TEC current monitor | | `tec_i` | Amperes | TEC output current feedback derived from `i_tec` | | `tec_u_meas` | Volts | Measurement of the voltage across the TEC | | `pid_output` | Amperes | PID control output |