From 218faa618209bbc22502c177b8d21e1631257e32 Mon Sep 17 00:00:00 2001
From: LongHairedHacker <sebastian@sebastians-site.de>
Date: Wed, 13 Jun 2018 01:56:57 +0200
Subject: [PATCH] Started work on firmware

---
 firmware/.gitignore    |  1 +
 firmware/Makefile      | 56 +++++++++++++++++++++++++++++++++++
 firmware/include/twi.h | 12 ++++++++
 firmware/main.c        | 17 +++++++++++
 firmware/twi.c         | 66 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 152 insertions(+)
 create mode 100644 firmware/.gitignore
 create mode 100644 firmware/Makefile
 create mode 100644 firmware/include/twi.h
 create mode 100644 firmware/main.c
 create mode 100644 firmware/twi.c

diff --git a/firmware/.gitignore b/firmware/.gitignore
new file mode 100644
index 0000000..ba077a4
--- /dev/null
+++ b/firmware/.gitignore
@@ -0,0 +1 @@
+bin
diff --git a/firmware/Makefile b/firmware/Makefile
new file mode 100644
index 0000000..30a03ce
--- /dev/null
+++ b/firmware/Makefile
@@ -0,0 +1,56 @@
+AVRMCU ?= atmega8
+F_CPU ?= 16000000
+ISPPORT ?= /dev/kaboard
+
+VERSION = 0.1
+
+HEADERS = include/twi.h
+SRC = main.c twi.c
+TARGET = cube-kl
+OBJDIR = bin
+
+CC = avr-gcc
+OBJCOPY = avr-objcopy
+OBJDUMP = avr-objdump
+SIZE = avr-size
+
+OBJ = $(SRC:%.c=$(OBJDIR)/$(AVRMCU)/%.o)
+
+CFLAGS = -I include -I images -I fonts -Os -Wall -Wstrict-prototypes
+CFLAGS += -ffunction-sections -fdata-sections
+CFLAGS += -fshort-enums -fpack-struct -funsigned-char -funsigned-bitfields
+CFLAGS += -mmcu=$(AVRMCU) -DF_CPU=$(F_CPU)UL -DVERSION=$(VERSION)
+
+LDFLAGS = -mmcu=$(AVRMCU) -Wl,--gc-sections
+
+all: start $(OBJDIR)/$(AVRMCU)/$(TARGET).hex size
+	@echo ":: Done !"
+
+start:
+	@echo "cube-kl firmware $(VERSION)"
+	@echo "==========================="
+	@echo ":: Building for $(AVRMCU)"
+	@echo ":: MCU operating frequency is $(F_CPU)Hz"
+
+$(OBJDIR)/$(AVRMCU)/%.o : %.c $(HEADERS) Makefile
+	@mkdir -p $$(dirname $@)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+$(OBJDIR)/$(AVRMCU)/$(TARGET).elf : $(OBJ)
+	$(CC) $(LDFLAGS) $+ -o $@
+
+$(OBJDIR)/$(AVRMCU)/$(TARGET).hex : $(OBJDIR)/$(AVRMCU)/$(TARGET).elf
+	$(OBJCOPY) -O ihex $< $@
+
+size : $(OBJDIR)/$(AVRMCU)/$(TARGET).elf
+	@echo
+	@$(SIZE) --mcu=$(AVRMCU) -C $(OBJDIR)/$(AVRMCU)/$(TARGET).elf
+	@echo
+
+clean :
+	@rm -rf $(OBJDIR)
+
+flash : all
+	avrdude -c arduino \
+		-p $(AVRMCU) -P $(ISPPORT) \
+        -U flash:w:$(OBJDIR)/$(AVRMCU)/$(TARGET).hex
diff --git a/firmware/include/twi.h b/firmware/include/twi.h
new file mode 100644
index 0000000..570e9ca
--- /dev/null
+++ b/firmware/include/twi.h
@@ -0,0 +1,12 @@
+#ifndef __TWI_H__
+#define __TWI_H__ __TWI_H__
+
+#include <stdint.h>
+
+#include <util/twi.h>
+
+
+void twi_init(void);
+uint8_t twi_write(uint8_t address, uint8_t data[], uint8_t len);
+
+#endif
diff --git a/firmware/main.c b/firmware/main.c
new file mode 100644
index 0000000..a05c051
--- /dev/null
+++ b/firmware/main.c
@@ -0,0 +1,17 @@
+#include <avr/io.h>
+#include <util/delay.h>
+
+#include "twi.h"
+
+int main(void) {
+
+    twi_init();
+
+    while(1) {
+        uint8_t data[] = {'T','E','S','T'};
+        twi_write(96, data, 4);
+        _delay_ms(10);
+    }
+
+    while(1);
+}
diff --git a/firmware/twi.c b/firmware/twi.c
new file mode 100644
index 0000000..ed4ca93
--- /dev/null
+++ b/firmware/twi.c
@@ -0,0 +1,66 @@
+#include "twi.h"
+
+void twi_init() {
+    // bitrate = 1600000MHz / (16 + 2 * TWBR * 4^TWPS)
+
+    // Overall prescaler 40 = 16 + 2 * 3 * 4^1
+    TWBR = 3;               // 2 * 3 = 6
+    TWSR |= (1 << TWPS0);   // 4
+
+}
+
+uint8_t twi_start(void) {
+    // Enable internal pull-ups
+    PORTC |= (1 << PC5) | (1 << PC4);
+
+    // Setup for sending start condition, trigger sending, keep TWI enabled
+    TWCR |= (1 << TWSTA) | (1 << TWINT) | (1 << TWEN);
+
+    // Poll for TWI unit to finish
+    while(!(TWCR & (1 << TWINT)));
+
+    // Check if start was succesfull
+    return (TW_STATUS != TW_START);
+}
+
+void twi_stop(void) {
+    // Setup for sending stop condition, trigger sending, keep TWI enabled
+    TWCR = (1 << TWSTO) | (1 << TWINT) | (1 << TWEN);
+}
+
+
+uint8_t twi_write(uint8_t address, uint8_t data[], uint8_t len) {
+    // Send start condition
+    if(twi_start()) {
+        return 1;
+    }
+
+    TWDR = address | TW_WRITE;       // We want to write to the slave
+    TWCR = (1 << TWINT) | (1 << TWEN);  // Trigger transmission, keep TWI enabled
+
+    // Wait for TWI unit to finish
+    while(!(TWCR & (1 << TWINT)));
+
+    // Make sure the slave has acked
+    if(TW_STATUS != TW_MT_SLA_ACK) {
+        return 1;
+    }
+
+    for(uint8_t i = 0; i < len; i++) {
+        TWDR = data[i];                     // Send actual data
+        TWCR = (1 << TWINT ) | (1 << TWEN); // Trigger transmission, keep TWI enabled
+
+        // Wait for TWI unit to finish
+        while(!(TWCR & (1 << TWINT)));
+
+        // Make sure the data has been acked
+        if(TW_STATUS != TW_MT_DATA_ACK) {
+            return 1;
+        }
+    }
+
+    // Send stop condition
+    twi_stop();
+
+    return 0;
+}