From 10bf54edb9c2a989f9bbf94836c57537c4a02345 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?King=20K=C3=A9vin?= Date: Mon, 13 Mar 2023 23:11:40 +0100 Subject: [PATCH] doc: document project --- README.md | 43 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 41 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 9125abf..8f54c9c 100644 --- a/README.md +++ b/README.md @@ -1,9 +1,48 @@ -this is a template firmware for [ESP32-S2](https://www.espressif.com/en/products/socs/esp32-s2)-based micro-controller projects. +this project is about interfacing the GM-1352 sound level meter using an ESP32-S2-based board, so to read the sound level measurements digitally. + +GM-1352 +======= + +the GM-1352 is the successor of the GM-1351, and very similar to it. +the main difference is that the power is not delivered by a 9V battery, but by 3x1.5V AA batteries. + +[CuVoodoo #030](https://www.cuvoodoo.info/cuvoodoo-030-audio-is-killing-the-music/) already explained how to interface it. +basically just tap on the lines between the MCU (a EFM8BB10F8G-QFN20) and LCD controller (a Chip-on-Board under a blob of epoxy). +there are test points available for that: + +- CS: chip select, to start data communication +- DATA: the actual data bits +- WR: the data clock (not periodic) + +there are additional test points to read (or assert) button presses: + +- 1: HOLD button (press low) +- 2: MIN/MAX button (press low) +- 3: POWER button (press low) + +there is another test point marked S, but I don't know what this is for. + +also note that the LCD has segments for Bluetooth and USB. +there might be variants of the GM-1352 with these options. board ===== -the board used is a [WEMOS](https://www.wemos.cc/en/latest/index.html) [S2 mini](https://www.wemos.cc/en/latest/s2/s2_mini.html). +this repository is the firmware for [ESP32-S2](https://www.espressif.com/en/products/socs/esp32-s2)-based [WEMOS](https://www.wemos.cc/en/latest/index.html) [S2 mini](https://www.wemos.cc/en/latest/s2/s2_mini.html) board. + +connect the GM-1352 to the S2 mini as follows: + +- B+ to 5V: to power or get power from the device +- B- to GND: ground reference +- POWER to 16: to wake up the S2 when the device is powered (the S2 will shut down shortly after the GM-1352) +- DATA to 18: this will be the SPI MOSI line to read the measurments +- CS to 33: this will be the SPI CS line to identify transactions +- WR to 35: this will be the SPI SCK line to clock the data bits (not periodic) + +I soldered wires to the pads, and broke them out on a 8-pin female header, located above the battery compartment. +this also to easily connect on row of the S2 mini to it on the back of the GM-1352. + +now you can power the sound level meter through the S2 mini USB port, and read the measurements over its serial CDC ACM interface. compile and flash =================