I am currently in the process of designing a watch based on the ESP32 microcontroller, specifically the 32Mb Wroom. My watch consists of an HMC588L magnetometer, SIM800L sim card module, GC9A01 display and a generic TF micro sd card reader. Many of the modules share common pins on the ESP32. Since, I am new to the microcontroller hobby, could someone tell me which pins to connect each module to? This would be greatly appreciated.
For the display see this tutorial... looks like an SPI device.
The HMC588L is an I2C device default pins 21 (SDA) & 22 (SCL) on the ESP32.
The SIM800L communicates via serial, so you will need to connect to one of the ESP32's serial ports (Tx - Rx, Rx - Tx).
For the SD card reader... depends, but if SPI then same pins as the display (will need an extra chip select pin), or if I2C then same pins as the HMC588L.
Power and GND to all devices.
The sd card reader is SPI. What extra chip are you referring to? I know how to connect each module with my only confusion being the card reader and magnetometer both using SPI and the same pins.
When using SPI each device has a "Chip Select" CS pin. You need to connect this to the ESP32 to enable that device (only one at a time)... so although the SPI communication pins can be shared, if you have 5 SPI devices you need 5 pins on the ESP32 to connect to each CS pin.
Which pins of the ESP32 wroom are CS/ Chip select pins?
The ESP32's CS SPI select pins are the pins designated by the programmer to be used as CS pins.
The natural CS pins of the ESP32 are GPIO_NUM_5 and GPIO_NUM_15, just look at a developer board schematic.
Most any unused GPIO pin can be used as a CS pin.
You can use any unused GPIO pins... the ESP32 is the master... it is selecting the other devices by setting their CS pins.
@abinaash, your topic moved to project guidance.
I wish to connect several modules to an ESP32 Wroom module. Which pins on it are the CS/ Chip select pins?
You should be able to use any GPIO pin that is available. Is that not how SPI works ?
Your two topics on the same or similar subject have been merged.
Please do not duplicate your questions as doing so wastes the time and effort of the volunteers trying to help you as they are then answering the same thing in different places.
Please create one topic only for your question and choose the forum category carefully. If you have multiple questions about the same project then please ask your questions in the one topic as the answers to one question provide useful context for the others, and also you won’t have to keep explaining your project repeatedly.
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Thank you.
I am sincerely, sorry sir. I had forgotten that I had made a post before asking here. I shall prevent this from recurring.
If you are really serious about your project, then comply with the following steps of SSS Strategical (Small Start Strategy) approach.
1. Connect only the SD Card With ESP32 as per Fig-1 (not tested) and perform data/read write operation with it. Search Net for Test Codes if needed.
Figure-1:
2. Disconnect SD Card and connect HMC558L (the Magnetometer) with ESP32 and perform its functionality check.
3. Disconnect HMC559 and connect GC9A01 and perform its functionality check.
4. Disconnect GC9A01 and connect SIM800L and perform its functionality check.
5. Disconnect SIM800L from ESP32. Connect SD Card Reader and HMC558L and record the data of HMC558L onto SD card; read the data back and show on Serial Monitor.
6. Connect GC9A01 Module with Step-5 and perform the functionality check.
7. Finally connect the SIM800L Module with Step-6 and do what your project dictates to do.
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