From b34b2810dbee02cf5fd6136654f5ff2ce3028718 Mon Sep 17 00:00:00 2001
From: finga <finga@onders.org>
Date: Tue, 8 Mar 2022 14:42:04 +0100
Subject: [PATCH] fw-rust: Handle data residing in the EEPROM

---
 firmware/rust/Makefile.toml | 14 +++++++++++++-
 firmware/rust/src/main.rs   | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/firmware/rust/Makefile.toml b/firmware/rust/Makefile.toml
index 166b05a..59d36fa 100644
--- a/firmware/rust/Makefile.toml
+++ b/firmware/rust/Makefile.toml
@@ -12,7 +12,7 @@ command = "avr-size"
 args = ["--format=avr", "--mcu=${MCU}", "target/avr-atmega328p/debug/clock-generator.elf"]
 
 [tasks.copy_flash]
-description = "Copy the flash"
+description = "Extract the flash"
 dependencies = ["build"]
 command = "avr-objcopy"
 args = ["-O", "ihex", "-j", ".text", "-j", ".data", "target/avr-atmega328p/debug/clock-generator.elf", "target/avr-atmega328p/debug/clock-generator.hex"]
@@ -23,6 +23,18 @@ dependencies = ["copy_flash", "size"]
 command = "avrdude"
 args = ["-p", "${MCU}", "-c", "${PROGRAMMER}", "-U", "flash:w:target/avr-atmega328p/debug/clock-generator.hex:a"]
 
+[tasks.copy_eeprom]
+description = "Extract the EEPROM"
+dependencies = ["build"]
+command = "avr-objcopy"
+args = ["--change-section-lma", ".eeprom=0", "-O", "ihex", "-j", ".eeprom", "target/avr-atmega328p/debug/clock-generator.elf", "target/avr-atmega328p/debug/clock-generator.eep"]
+
+[tasks.eeprom]
+description = "Flash the eeprom"
+dependencies = ["copy_eeprom", "size"]
+command = "avrdude"
+args = ["-p", "${MCU}", "-c", "${PROGRAMMER}", "-U", "eeprom:w:target/avr-atmega328p/debug/clock-generator.eep:a"]
+
 [tasks.fuses]
 description = "Burn the fuses"
 command = "avrdude"
diff --git a/firmware/rust/src/main.rs b/firmware/rust/src/main.rs
index 431bdd9..8b9338d 100644
--- a/firmware/rust/src/main.rs
+++ b/firmware/rust/src/main.rs
@@ -16,6 +16,14 @@ use embedded_hal::{
 use nb::block;
 use panic_halt as _;
 
+#[used]
+#[link_section = ".eeprom"]
+static CONTRAST: u8 = 8;
+
+#[used]
+#[link_section = ".eeprom"]
+static BACKLIGHT: u8 = 1;
+
 // TODO: Use https://github.com/rust-lang/rust/issues/85077 when stabilized
 static SACRED_CHAO: [[u8; 40]; 5] = [
     [
@@ -64,11 +72,35 @@ static ONDERS_ORG: [[u8; 48]; 2] = [
 #[atmega_hal::entry]
 fn main() -> ! {
     interrupt::free(|_cs| {
-        // Get peripherals, pins and delay
+        // Get peripherals, pins, eeprom and delay
         let dp = Peripherals::take().unwrap();
         let pins = pins!(dp);
+        let eeprom = dp.EEPROM;
         let mut delay = Delay::<MHz8>::new();
 
+        // TODO: Wait for completion of previous write
+        // Write address into eeprom address register
+        eeprom
+            .eear
+            .write(|w| unsafe { w.bits(&CONTRAST as *const u8 as u16) });
+        // Start to read from eeprom by setting EERE
+        eeprom.eecr.write(|w| w.eere().set_bit());
+        // Return data from eeprom data register
+        let _contrast = eeprom.eedr.read().bits();
+
+        // TODO: Remove delay when waiting for completion of revious write is done
+        delay.delay_ms(1_u8);
+
+        // TODO: Wait for completion of previous write
+        // Write address into eeprom address register
+        eeprom
+            .eear
+            .write(|w| unsafe { w.bits(&BACKLIGHT as *const u8 as u16) });
+        // Start to read from eeprom by setting EERE
+        eeprom.eecr.write(|w| w.eere().set_bit());
+        // Return data from eeprom data register
+        let _backlight = eeprom.eedr.read().bits();
+
         // Init display backlight
         let tc0 = dp.TC0;
         tc0.tccr0a.write(|w| {