1 files changed, 135 insertions, 0 deletions
diff --git a/ao-bringup-avr/ao-uart.c b/ao-bringup-avr/ao-uart.c
new file mode 100644
index 00000000..3c290c1a
--- /dev/null
+++ b/ao-bringup-avr/ao-uart.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright © 2011 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#define TEENSY 1
+#if TEENSY
+#define F_CPU 16000000UL	// 16 MHz
+#else
+#define F_CPU  8000000UL	// 8 MHz
+#endif
+#include <util/delay.h>
+
+#define LEDOUT		PORTB7
+#define LEDPORT		PORTB
+#define LEDDDR		DDRB
+#define LEDDDRPIN	DD7
+
+static void
+timer1_init(void)
+{
+	TCCR1A = ((0 << WGM11) |	/* CTC mode, OCR1A */
+		  (0 << WGM10));	/* CTC mode, OCR1A */
+	TCCR1B = ((0 << ICNC1) |	/* no input capture noise canceler */
+		  (0 << ICES1) |	/* input capture on falling edge (don't care) */
+		  (0 << WGM13) |	/* CTC mode, OCR1A */
+		  (1 << WGM12) |	/* CTC mode, OCR1A */
+		  (3 << CS10));		/* clk/64 from prescaler */
+
+#if TEENSY
+	OCR1A = 2500;			/* 16MHz clock */
+#else
+	OCR1A = 1250;			/* 8MHz clock */
+#endif
+
+	TIMSK1 = (1 << OCIE1A);		/* Interrupt on compare match */
+}
+
+static void
+clock_init(void)
+{
+	/* disable RC clock */
+	CLKSEL0 &= ~(1 << RCE);
+
+	/* Disable PLL */
+	PLLCSR &= ~(1 << PLLE);
+
+	/* Enable external clock */
+	CLKSEL0 |= (1 << EXTE);
+
+	/* wait for external clock to be ready */
+	while ((CLKSTA & (1 << EXTON)) == 0)
+		;
+
+	/* select external clock */
+	CLKSEL0 |= (1 << CLKS);
+
+	/* Disable the clock prescaler */
+	cli();
+	CLKPR = (1 << CLKPCE);
+	CLKPR = 0;
+	sei();
+
+	/* Set up the PLL to use the crystal */
+
+	/* Use primary system clock as PLL source */
+	PLLFRQ = ((0 << PINMUX) |	/* Use primary clock */
+		  (0 << PLLUSB) |	/* No divide by 2 for USB */
+		  (0 << PLLTM0) |	/* Disable high speed timer */
+		  (0x4 << PDIV0));	/* 48MHz PLL clock */
+
+	/* Set the frequency of the crystal */
+#if TEENSY
+	PLLCSR |= (1 << PINDIV);	/* For 16MHz crystal on Teensy board */
+#else
+	PLLCSR &= ~(1 << PINDIV);	/* For 8MHz crystal on TeleScience board */
+#endif
+
+	/* Enable the PLL */
+	PLLCSR |= (1 << PLLE);
+	while (!(PLLCSR & (1 << PLOCK)))
+		;
+}
+
+void
+uart_send(char data)
+{
+	while (!(UCSR1A & (1 << UDRE1)))
+		;
+	UDR1 = data;
+}
+
+void
+uart_init(uint16_t baud)
+{
+	PRR1 &= ~(1 << PRUSART1);
+	UBRR1L = baud;
+	UBRR1H = baud >> 8;
+	UCSR1A = 0;
+	UCSR1B = ((1 << RXEN1) |	/* Enable receiver */
+		  (1 << TXEN1));	/* Enable transmitter */
+	UCSR1C = ((0 << UMSEL10) |	/* Asynchronous mode */
+		  (0 << UPM10) |	/* No parity */
+		  (0 << USBS1) |	/* 1 stop bit */
+		  (3 << UCSZ10) |	/* 8 bit characters */
+		  (0 << UCPOL1));	/* MBZ for async mode */
+}
+
+int main(void)
+{
+	clock_init();
+	timer1_init();
+	uart_init(832);
+
+	LEDDDR |= (1 << LEDDDRPIN);
+
+	for (;;) {
+		LEDPORT ^= (1 << LEDOUT);
+		uart_send('H');
+	}
+}