From 68f6d98f1f07cdab475652349a258233e555bd1e Mon Sep 17 00:00:00 2001
From: Alexander Heldt <me@alexanderheldt.se>
Date: Wed, 1 Jan 2025 12:39:17 +0100
Subject: [PATCH] Add `README`

---
 README.md | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 README.md

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..cc2b9e9
--- /dev/null
+++ b/README.md
@@ -0,0 +1,35 @@
+# Falling sand on the STM32F411CE
+
+## Building
+Run
+```sh
+make build
+```
+
+## Probe for the board
+Run
+```sh
+st-info --probe
+```
+
+## Flashing
+Run
+```sh
+make flash
+```
+
+## Debugging
+
+### `st-info --probe` shows 0KB flash
+```
+> sudo st-info --probe
+Found 1 stlink programmers
+  version:    V2J43S28
+  serial:     0671FF343056363043090732
+  flash:      0 (pagesize: 16384)      <--- 0KB flash
+  sram:       131072
+  chipid:     0x431
+  dev-type:   STM32F411xC_xE
+```
+This can happen when the flash is locked. One way to unlock it is to erase the entire chip via the
+Windows application `ST-Link Util`.