This folder contains some examples to show how to read temperature from MAX6675 converter. The examples have been prepared when developing Toit package with MAX6675 driver.
- max6675-bit-bang.toit - An example of reading MAX6675 converter using bit-banging of ESP32 GPIO pins.
- max6675-spi.toit - An example reading the MAX6675 converter usig the native SPI interface of ESP32.
- max667.toit - A simple example to read MAX6675 converter using a driver implemented in a separate package.
The application uses the following connection between ESP32 and MAX6675 converter.
| Signal Name | ESP32 Pin | MAX6675 Pin |
|---|---|---|
| Chip select (CS) | 12 | CS |
| Serial output (SO) | 13 | SO |
| Serial clock (SCK) | 14 | SCK |
| Ground | GND | GND |
| Power Supply 3.3 V | VCC |
Open a terminal and flash the Jaguar image to ESP32 board. Provide SSID and PASSWORD to your Wi-Fi network. If you have more than one ESP32 board connected to your computer, you will be asked to select the port name of the specific ESP32 board to flash the image.
jag config wifi set --wifi-ssid SSID --wifi-password PASSWORD
Upload max6675-spi.toit application to the ESP32 board. Note the upload will be done using the Wi-Fi network specified in the previous step.
jag watch max6675-spi.toit
By using watch we instruct Jaguar to "watch" the application source file for any changes. If a change is detected Jaguar will compile and upload the update to the ESP32.
Open another terminal and run the following command to monitor the application output.
jag monitor
You should see a similar output in the terminal:
Starting serial monitor of port 'COM3' ...
ets Jun 8 2016 00:22:57
rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
ets Jun 8 2016 00:22:57
rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 188777542, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:188
ho 0 tail 12 room 4
load:0x40078000,len:12180
load:0x40080400,len:2936
entry 0x400805c8
clearing RTC memory: RTC memory is in inconsistent state
[flash reg] address 0x3f430000, size 0x00200000
[jaguar] INFO: program 1 re-starting from flash @ [0,28672]
Temperature: 33.0°C
[wifi] DEBUG: connecting
Temperature: 32.2°C
Temperature: 32.8°C
Temperature: 32.5°C
Temperature: 32.8°C
[wifi] DEBUG: connected
Temperature: 32.5°C
[wifi] INFO: got ip ip=192.168.1.17
[jaguar] INFO: running Jaguar device 'max6675' (id: 'fd35b832-e0b5-44fb-85e5-0fa22199f56c') on 'http://192.168.1.17:9000'
Temperature: 32.2°C
Temperature: 32.2°C
Temperature: 32.8°C
...
If the SPI interface of ESP32 is occupied by another device you can upload max6675-bit-bang.toit instead.
To use the example that implements a driver in an external package, first install the package.
jag pkg install github.com/krzychb/toit-max6675
Then load the example as described in previous steps.
Reading MAX6675 Using bit-banging of GPIO pins of ESP32
Reading MAX6675 using the SPI interface of ESP32
- MAX6675 Datasheet - MAX6675 Cold-Junction-Compensated K-Thermocouple-to-Digital Converter
- MAX6675 Calculator - MS Excel spreadsheet to calculate the temperature based on bit pattern read from MAX6675 converter