274 lines
12 KiB
Markdown
274 lines
12 KiB
Markdown
# Firmware for the Sinara 8451 Thermostat
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- [x] [Continuous Integration](https://nixbld.m-labs.hk/job/mcu/thermostat/thermostat)
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- [x] Download latest firmware build: [ELF](https://nixbld.m-labs.hk/job/mcu/thermostat/thermostat/latest/download/1) [BIN](https://nixbld.m-labs.hk/job/mcu/thermostat/thermostat/latest/download/2)
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## Building
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### Reproducible build with Nix
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Thermostat firmware is packaged using the [Nix](https://nixos.org) Flakes system. Install Nix 2.4+ and enable flakes by adding ``experimental-features = nix-command flakes`` to ``nix.conf`` (e.g. ``~/.config/nix/nix.conf``).
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Once you have Flakes enabled, you can use ``nix build`` to build the firmware.
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### Development environment
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Clone this repository and with Nix Flakes enabled, use the following commands:
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```shell
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nix develop
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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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Alternatively, you can install the Rust toolchain without Nix using rustup; see the Rust manifest file pulled in `flake.nix` to determine which Rust version to use.
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## Debugging
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Connect SWDIO/SWCLK/RST/GND to a programmer such as ST-Link v2.1. Run OpenOCD:
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```shell
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openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg
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```
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You may need to power up the programmer before powering the device.
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Leave OpenOCD running. Run the GNU debugger:
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```shell
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gdb target/thumbv7em-none-eabihf/release/thermostat
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(gdb) source openocd.gdb
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```
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## Flashing
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There are several options for flashing Thermostat. DFU requires only a micro-USB connector, whereas OpenOCD needs a JTAG/SWD adapter.
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### dfu-util on Linux
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* Install the DFU USB tool (dfu-util).
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* Convert firmware from ELF to BIN: `arm-none-eabi-objcopy -O binary thermostat thermostat.bin` (you can skip this step if using the BIN from Hydra)
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* Connect to the Micro USB connector to Thermostat below the RJ45.
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* Add jumper to Thermostat v2.0 across 2-pin jumper adjacent to JTAG connector.
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* Cycle board power to put it in DFU update mode
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* Push firmware to flash: `dfu-util -a 0 -s 0x08000000:leave -D thermostat.bin`
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* Remove jumper
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* Cycle power to leave DFU update mode
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### st.com DfuSe tool on Windows
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On a Windows machine install [st.com](https://st.com) DfuSe USB device firmware upgrade (DFU) software. [link](https://www.st.com/en/development-tools/stsw-stm32080.html).
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- add jumper to Thermostat v2.0 across 2-pin jumper adjacent to JTAG connector
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- cycle board power to put it in DFU update mode
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- connect micro-USB to PC
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- use st.com software to upload firmware
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- remove jumper
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- cycle power to leave DFU update mode
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### OpenOCD
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```shell
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openocd -f interface/stlink-v2-1.cfg -f target/stm32f4x.cfg -c "program target/thumbv7em-none-eabihf/release/thermostat verify reset;exit"
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```
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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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rlwrap 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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### TCP commands
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Send commands as simple text string terminated by `\n`. Responses are
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formatted as line-delimited JSON.
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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 <amp>` | Set maximum positive output current |
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| `pwm <0/1> max_i_neg <amp>` | Set maximum negative output current |
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| `pwm <0/1> max_v <volt>` | Set maximum output voltage |
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| `pwm <0/1> i_set <amp>` | Disengage PID, set fixed output current |
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| `pwm <0/1> pid` | Let output current to be controlled by the PID |
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| `center <0/1> <volt>` | Set the MAX1968 0A-centerpoint to the specified fixed voltage |
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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 <deg_celsius>` | Set the PID controller target temperature |
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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 <amp>` | Set mininum output |
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| `pid <0/1> output_max <amp>` | 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 [0/1]` | Restore configuration for channel all/0/1 from flash |
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| `save [0/1]` | Save configuration for channel all/0/1 to flash |
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| `reset` | Reset the device |
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| `dfu` | Reset device and enters USB device firmware update (DFU) mode |
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| `ipv4 <X.X.X.X/L> [Y.Y.Y.Y]` | Configure IPv4 address, netmask length, and optional default gateway |
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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 when USB 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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### 50/60 Hz filtering
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The AD7172-2 ADC on the SENS inputs supports simultaneous rejection of
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50 Hz ± 1 Hz and 60 Hz ± 1 Hz (dB). Affecting sampling rate, the
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postfilter rate can be tuned with the `postfilter` command.
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| Postfilter rate | Rejection | Effective sampling rate |
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| --- | :---: | --- |
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| 16.67 Hz | 92 dB | 8.4 Hz |
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| 20 Hz | 86 dB | 9.1 Hz |
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| 21.25 Hz | 62 dB | 10 Hz |
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| 27 Hz | 47 dB | 10.41 Hz |
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## Thermo-Electric Cooling (TEC)
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- Connect TEC module device 0 to TEC0- and TEC0+.
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- Connect TEC module device 1 to TEC1- and TEC1+.
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- The GND pin is for shielding not for sinking TEC module currents.
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When using a TEC module with the Thermostat, the Thermostat expects the thermal load (where the thermistor is located) to heat up with a positive software current set point, and cool down with a negative current set point.
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Testing heat flow direction with a low set current is recommended before installation of the TEC module.
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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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| `i_set` | Amperes | (Not a limit; Open-loop mode) |
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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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Example: set the maximum negative current of channel 0 to -3 A.
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```
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pwm 0 max_i_neg 3
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```
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Example: set the maximum positive current of channel 1 to 3 A.
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```
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pwm 0 max_i_pos 3
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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 i_set 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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## PID Tuning
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The thermostat implements a PID control loop for each of the TEC channels, more details on setting up the PID control loop can be found [here](./doc/PID%20tuning.md).
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