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