From 89be54a9feb65bfbad237b79969bf3446c90eebd Mon Sep 17 00:00:00 2001
From: Dennis Brentjes <d.brentjes@gmail.com>
Date: Sat, 28 Mar 2020 20:30:24 +0100
Subject: Adds initial version of the Attiny24 firmware

---
 picl-firmware/.vscode/c_cpp_properties.json | 15 +++++
 picl-firmware/.vscode/tasks.json            | 26 +++++++++
 picl-firmware/fan_control.c                 | 86 +++++++++++++++++++++++++++++
 picl-firmware/picl-firmware.code-workspace  |  8 +++
 4 files changed, 135 insertions(+)
 create mode 100644 picl-firmware/.vscode/c_cpp_properties.json
 create mode 100644 picl-firmware/.vscode/tasks.json
 create mode 100644 picl-firmware/fan_control.c
 create mode 100644 picl-firmware/picl-firmware.code-workspace

(limited to 'picl-firmware')

diff --git a/picl-firmware/.vscode/c_cpp_properties.json b/picl-firmware/.vscode/c_cpp_properties.json
new file mode 100644
index 0000000..add3b91
--- /dev/null
+++ b/picl-firmware/.vscode/c_cpp_properties.json
@@ -0,0 +1,15 @@
+{
+    "configurations": [
+        {
+            "name": "AVR",
+            "includePath": [
+                "${workspaceFolder}/**",
+                "/usr/avr/include/**"
+            ],
+            "defines": ["__AVR_ATtiny24__"],
+            "compilerPath": "/usr/bin/avr-gcc",
+            "intelliSenseMode": "clang-x64"
+        }
+    ],
+    "version": 4
+}
\ No newline at end of file
diff --git a/picl-firmware/.vscode/tasks.json b/picl-firmware/.vscode/tasks.json
new file mode 100644
index 0000000..069c853
--- /dev/null
+++ b/picl-firmware/.vscode/tasks.json
@@ -0,0 +1,26 @@
+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558 
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "type": "shell",
+            "label": "avr-gcc build active file",
+            "command": "/bin/avr-gcc",
+            "args": [
+                "-mmcu=attiny24",
+                "-g",
+                "${file}",
+                "-o",
+                "${fileDirname}/${fileBasenameNoExtension}"
+            ],
+            "options": {
+                "cwd": "/bin"
+            },
+            "problemMatcher": [
+                "$gcc"
+            ],
+            "group": "build"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/picl-firmware/fan_control.c b/picl-firmware/fan_control.c
new file mode 100644
index 0000000..9e87963
--- /dev/null
+++ b/picl-firmware/fan_control.c
@@ -0,0 +1,86 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/sleep.h>
+
+void setup_adc() {
+    //enable interrupts
+    sei();
+    // setup external reference voltage.
+    ADMUX &= ~(3UL << REFS0);
+    ADMUX |= (1UL << REFS0);
+    // set left adjusted ADC result so we can easily only use the upper 8 bits of the result
+    ADCSRB |= (1UL << ADLAR);
+    // enable ADC interrupt
+    ADCSRA |= (1UL << ADIE);
+}
+
+void setup_timers() {
+    //use system clock for timers, no prescaler.
+    TCCR0B &= ~(7UL << CS00);
+    TCCR0B |= (1UL << CS00);
+
+    //set mode 5 (PWM, phase correct, top defined by OCRA)
+    TCCR0A &= ~(3UL << WGM00);
+    TCCR0B &- ~(1UL << WGM02);
+    TCCR0A |= (1UL << WGM00);
+    TCCR0B |= (1UL << WGM02);
+}
+
+void enable_ADC() {
+    PRR &= ~(1UL << PRADC);
+    ADCSRA |= (1UL << ADEN);
+}
+
+void disable_ADC() {
+    ADCSRA &= ~(1UL << ADEN);
+    PRR |= (1UL << PRADC);
+}
+
+void select_ADC_channel(int channel) {
+    ADMUX &= ~(7UL << MUX0);
+    ADMUX |= (channel << MUX0);
+}
+
+uint8_t get_ADC_result() {
+    uint8_t result = ADCL;
+    //conversion would be blocked if we don't also read ADCH although we won't use the upper 2 bits.
+    uint8_t unblock = ADCH; 
+    return result;
+}
+
+void start_ADC() {
+    ADCSRA |= (1UL << ADSC);
+}
+
+volatile uint8_t fan1;
+volatile uint8_t fan2;
+
+void start_polling_fans() {
+    PRR &= ~(1UL << PRADC);
+    enable_ADC();
+    select_ADC_channel(ADC1D);
+    start_ADC();
+}
+
+ISR(ADC_vect) {
+    if(ADMUX & (7UL << MUX0) == ADC1D) {
+        fan1 = get_ADC_result();
+        select_ADC_channel(ADC2D);
+        start_ADC();
+        return;
+    }
+
+    if(ADMUX & (7UL << MUX0) == ADC2D) {
+        fan2 = get_ADC_result();
+        disable_ADC();
+        return;
+    }
+}
+
+int main() {
+    set_sleep_mode(0);
+    setup_adc();
+    setup_timers();
+
+    while(1);
+}
diff --git a/picl-firmware/picl-firmware.code-workspace b/picl-firmware/picl-firmware.code-workspace
new file mode 100644
index 0000000..876a149
--- /dev/null
+++ b/picl-firmware/picl-firmware.code-workspace
@@ -0,0 +1,8 @@
+{
+	"folders": [
+		{
+			"path": "."
+		}
+	],
+	"settings": {}
+}
\ No newline at end of file
-- 
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