From 20372fb78cb8ead2565ed863dd456b53b2b8a89c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Tue, 21 Jun 2022 14:59:19 +0200
Subject: [PATCH] doc: document project

---
 README | 44 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/README b/README
index bb750e7..4433af6 100644
--- a/README
+++ b/README
@@ -1,2 +1,42 @@
-firmware template for ST STM8S micro-controller.
-includes register definitions using macros and structures.
+This is the firmware for the [HDMI firewall programmer](https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_firewall_programmer).
+The HDMI firewall programmer copies EDID information onto the [HDMI firewall](https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_firewall).
+
+usage
+=====
+
+see [hardware description](https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_firewall_programmer/README.md).
+
+mode of operation
+=================
+
+the EDID can be accessed using the I²C lines on the HDMI port.
+the firmware reads and writes the data from slave device address 0x50.
+
+connections
+===========
+
+the programmer can be flashed using the micro-USB port (not USB signals):
+
+- the SWIM signal is on USB pin 2 D-
+- the NRST signal is on USB pin 4 ID
+
+there is also debugging output using UART (115200 8N1) on STM8S pin 2 PD5/UART_TX.
+
+code
+====
+
+the source code is for a STM8S103F3 micro-controller.
+
+compile
+=======
+
+requirement: SDCC, make
+
+to compile the source code into a firmware, run `make`.
+
+flash
+=====
+
+requirement: stm8flash, a ST-LINK/V2 programmer
+
+to flash the firmware on the micro-controller, run `make flash`.