add preliminary arduino nano dmx driver

note that it disables stdout / kout support, as the ATMega328 only has one
UART.

1 files changed, 52 insertions, 0 deletions

diff --git a/src/arch/arduino-nano/driver/dmx.cc b/src/arch/arduino-nano/driver/dmx.cc
new file mode 100644
index 0000000..20a7332
--- /dev/null
+++ b/src/arch/arduino-nano/driver/dmx.cc
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2022 Daniel Friesel
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+#include <avr/io.h>
+#include "arch.h"
+#include "driver/dmx.h"
+#include "driver/gpio.h"
+
+#define BAUD 250000UL
+#include <util/setbaud.h>
+
+void DMX::setup()
+{
+	UBRR0H = UBRRH_VALUE;
+	UBRR0L = UBRRL_VALUE;
+
+#if USE_2X
+	UCSR0A |= _BV(U2X0);
+#else
+	UCSR0A &= ~_BV(U2X0);
+#endif
+
+	UCSR0B |= _BV(TXEN0);
+	UCSR0C = _BV(USBS0) | _BV(UCSZ01) | _BV(UCSZ00); // 8 bits
+}
+
+void DMX::write()
+{
+	// Disable UART for reset and mark signals
+	UCSR0B &= ~_BV(TXEN0);
+	gpio.output(GPIO::pd1, 0);
+	arch.delay_us(88); // break
+	gpio.output(GPIO::pd1, 1);
+	arch.delay_us(8);
+	UCSR0B |= _BV(TXEN0); // causes line to go high
+	for (uint8_t i = 0; i < 16; i++) {
+		while (!(UCSR0A & _BV(UDRE0)));
+		UDR0 = frames[i];
+	}
+	for (uint8_t i = 0; i < 241; i++) {
+		while (!(UCSR0A & _BV(UDRE0)));
+		UDR0 = 0;
+	}
+	for (uint8_t i = 0; i < 255; i++) {
+		while (!(UCSR0A & _BV(UDRE0)));
+		UDR0 = 0;
+	}
+}
+
+DMX dmx;