From 122c0e6c35936bb0f5e6b51fe8528122abf02cac Mon Sep 17 00:00:00 2001
From: Ain <41307858+nero@users.noreply.github.com>
Date: Mon, 29 Jan 2018 00:50:22 +0000
Subject: [PATCH] Factor uart code into separate driver code

---
 drivers/uart.c          | 10 ++++++++++
 drivers/uart.h          |  0
 drivers/uart_rx_async.c | 16 ++++++++++++++++
 drivers/uart_rx_async.h |  3 +++
 uart-relaycard.c        | 16 ++--------------
 5 files changed, 31 insertions(+), 14 deletions(-)
 create mode 100644 drivers/uart.c
 create mode 100644 drivers/uart.h
 create mode 100644 drivers/uart_rx_async.c
 create mode 100644 drivers/uart_rx_async.h

diff --git a/drivers/uart.c b/drivers/uart.c
new file mode 100644
index 0000000..16ab1ea
--- /dev/null
+++ b/drivers/uart.c
@@ -0,0 +1,10 @@
+#include "uart.h"
+#include <avr/io.h>
+
+#define BAUD_PRESCALE (((F_CPU/(BAUDRATE*8UL)))-1)
+
+void __attribute__ ((naked)) __attribute__ ((section (".init5"))) uart_init() {
+  UCSR0A = (1<<U2X0);
+  UCSR0C = (1<<UCSZ00) | (1<<UCSZ01); // 8N1
+  UBRR0 = BAUD_PRESCALE;
+}
diff --git a/drivers/uart.h b/drivers/uart.h
new file mode 100644
index 0000000..e69de29
diff --git a/drivers/uart_rx_async.c b/drivers/uart_rx_async.c
new file mode 100644
index 0000000..0b69f59
--- /dev/null
+++ b/drivers/uart_rx_async.c
@@ -0,0 +1,16 @@
+#include "uart_rx_async.h"
+#include "uart.h"
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+void __attribute__ ((naked)) __attribute__ ((section (".init6"))) uart_rx_async_init() {
+  UCSR0B = (1<<RXEN0) | (1<<RXCIE0);
+}
+
+void __attribute__ ((naked)) __attribute__ ((section (".init8"))) uart_rx_sei() {
+  sei();
+}
+
+ISR(USART_RX_vect) {
+  uart_process(UDR0);
+}
diff --git a/drivers/uart_rx_async.h b/drivers/uart_rx_async.h
new file mode 100644
index 0000000..9335cd4
--- /dev/null
+++ b/drivers/uart_rx_async.h
@@ -0,0 +1,3 @@
+#include <stdint.h>
+
+extern void uart_process(uint8_t c);
diff --git a/uart-relaycard.c b/uart-relaycard.c
index 78deee6..c6bacf4 100644
--- a/uart-relaycard.c
+++ b/uart-relaycard.c
@@ -1,9 +1,7 @@
 #include <stdio.h>
 #include <avr/io.h>
 #include <util/delay.h>
-#include <avr/interrupt.h>
-
-#define BAUD_PRESCALE (((F_CPU/(BAUDRATE*8UL)))-1)
+#include "drivers/uart_rx_async.h"
 
 /* Button matrix between PB3-PB4, PC0-PC3
  * PC0-PC3 are inputs, default pull-up
@@ -70,8 +68,7 @@ void setrelay(uint8_t n, uint8_t s) {
 }
 
 char umode = 't';
-ISR(USART_RX_vect) {
-        uint8_t c = UDR0;
+void uart_process(uint8_t c) {
 	if (c == 't' || c == 'e' || c == 'd') {
 		umode = c;
 	} else if (c >= '0' && c <= '7') {
@@ -99,15 +96,6 @@ int main() {
 	PORTD |= 0b11111100;
 	PORTB |= 0b00000011;
 
-	// Init uart
-        UCSR0A = (1<<U2X0);
-	// Transmit is enabled to set PIN levels, but we will never write
-        UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
-        UCSR0C = (1<<UCSZ00) | (1<<UCSZ01); // 8N1
-        UBRR0 = BAUD_PRESCALE;
-
-	sei();
-
 	// Now handle button inputs
 	uint8_t c,p,d,i;
 	p = 0;