From 0ff109f1fd0bcd39b1ce4e950dba3f1c7523a861 Mon Sep 17 00:00:00 2001
From: Sadeep Madurange <sadeep@asciimx.com>
Date: Sat, 3 May 2025 07:21:28 +0800
Subject: Initial commit.

---
 Soft_UART_Timer1.h | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 Soft_UART_Timer1.h

(limited to 'Soft_UART_Timer1.h')

diff --git a/Soft_UART_Timer1.h b/Soft_UART_Timer1.h
new file mode 100644
index 0000000..4ad8669
--- /dev/null
+++ b/Soft_UART_Timer1.h
@@ -0,0 +1,115 @@
+/*
+ * Soft_UART_Timer1.h
+ *
+ * Software UART for ATmega328p using Timer1
+ * 
+ * Now only tranmission, no receiving
+ */ 
+
+#ifndef SOFTUARTTIMER1_H_
+#define SOFTUARTTIMER1_H_
+
+//////////////////////////////////////////////////////////////////////////
+// Usage (in your .c file):
+// 1. define Tx pin: DDR register, PORT register, PIN number:
+// #define Soft_UART_TX_PORT PORTD
+// #define Soft_UART_TX_DDR DDRD
+// #define Soft_UART_TX_PIN 3
+// 2. define UART speed
+// #define Soft_UART_Baud 9600
+// 3. include .h file:
+// #include "Soft_UART_Timer1.h"
+// 3. initialize software UART, required to call before usage other functions:
+// static void Soft_UART_init(void);
+// 4. send byte
+// static void Soft_UART_send_byte(char byte);
+// this function send byte in background,
+// only one byte in background, other will wait.
+//////////////////////////////////////////////////////////////////////////
+
+
+//////////////////////////////////////////////////////////////////////////
+// From this line begins code to the end of file.
+// All code written in .h file for better inline optimization.
+// Try to include this file only once per project.
+//////////////////////////////////////////////////////////////////////////
+
+volatile char Soft_UART_busy_flag=0;
+char Soft_UART_next_byte=0;
+
+//////////////////////////////////////////////////////////////////////////
+// Initialization software UART, required to call before usage
+//////////////////////////////////////////////////////////////////////////
+static void Soft_UART_init(void)
+{   // Pin init
+	bit_set(Soft_UART_TX_DDR,Soft_UART_TX_PIN);
+	bit_set(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
+	// Timer1 init
+	TCCR1A=(0<<COM1A1)|(0<<COM1A0)|(0<<COM1B1)|(0<<COM1B0)|(1<<WGM11)|(0<<WGM10);
+	TCCR1B=(0<<ICNC1)|(0<<ICES1)|(1<<WGM13)|(1<<WGM12)|(0<<CS12)|(0<<CS11)|(0<<CS10); // prescaler 0, timer stopped
+	TCCR1C=(0<<FOC1A)|(0<<FOC1B);
+	TIMSK1=(0<<ICIE1)|(0<<OCIE1B)|(0<<OCIE1A)|(0<<TOIE1);
+	//ICR1=1666;
+	ICR1=F_CPU/Soft_UART_Baud;
+}
+
+//////////////////////////////////////////////////////////////////////////
+// Internal function, start timer, when need to send something
+//////////////////////////////////////////////////////////////////////////
+static void Soft_UART_Timer1_start(void)
+{
+	bit_set(TIMSK1,TOIE1);
+	bit_set(TCCR1B,CS10);
+}
+
+//////////////////////////////////////////////////////////////////////////
+// Internal function, stop timer, when nothing to send
+//////////////////////////////////////////////////////////////////////////
+static void Soft_UART_Timer1_stop(void)
+{
+	bit_clr(TIMSK1,TOIE1);
+	bit_clr(TCCR1B,CS10);
+}
+
+//////////////////////////////////////////////////////////////////////////
+// Send byte in background, only one byte in background, other - wait
+//////////////////////////////////////////////////////////////////////////
+static void Soft_UART_send_byte(char byte)
+{
+	while(Soft_UART_busy_flag)
+		;
+	Soft_UART_busy_flag=1;
+	Soft_UART_Timer1_start();
+	Soft_UART_next_byte=byte;
+}
+
+//////////////////////////////////////////////////////////////////////////
+// Internal function, send next bit
+//////////////////////////////////////////////////////////////////////////
+ISR(TIMER1_OVF_vect)
+{
+	static char Soft_UART_pos=0;
+	switch(Soft_UART_pos)
+		{
+			case 0: // send START bit
+					bit_clr(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
+					break;
+			case 9:	// send STOP bit
+					bit_set(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
+					break;
+			case 10:// end of transmission
+					Soft_UART_busy_flag=0;
+					Soft_UART_pos=0;
+					Soft_UART_Timer1_stop();
+					return;
+			default:// send data bit
+					if(bit_tst(Soft_UART_next_byte,Soft_UART_pos-1))
+						bit_set(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
+					else
+						bit_clr(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
+					break;
+		}
+	Soft_UART_pos++;
+	bit_change(PORTB,5);
+}
+#endif /* SOFTUARTTIMER1_H_ */ 
-- 
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