altos: Make micropeak 'serial' interface work

I prototyped the mpserial interface on a breadboard and tuned the
circuit to register the LED correctly. Then adjusted the serial code
to send bits at the right speed and format.

The logging contents are now in hexdecimal with a CCITT CRC-16
computed to verify correct reception.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 54 insertions, 1 deletions

diff --git a/src/micropeak/ao_log_micro.c b/src/micropeak/ao_log_micro.c
index 40a7a35d..d665efb5 100644
--- a/src/micropeak/ao_log_micro.c
+++ b/src/micropeak/ao_log_micro.c
@@ -49,6 +49,46 @@ ao_log_micro_data(void)
 	}
 }
 
+#define POLY 0x8408
+
+static uint16_t
+ao_log_micro_crc(uint16_t crc, uint8_t byte)
+{
+	uint8_t	i;
+
+	for (i = 0; i < 8; i++) {
+		if ((crc & 0x0001) ^ (byte & 0x0001))
+			crc = (crc >> 1) ^ POLY;
+		else
+			crc = crc >> 1;
+		byte >>= 1;
+	}
+	return crc;
+}
+
+static void
+ao_log_hex_nibble(uint8_t b)
+{
+	if (b < 10)
+		ao_async_byte('0' + b);
+	else
+		ao_async_byte('a' - 10 + b);
+}
+
+static void
+ao_log_hex(uint8_t b)
+{
+	ao_log_hex_nibble(b>>4);
+	ao_log_hex_nibble(b&0xf);
+}
+
+static void
+ao_log_newline(void)
+{
+	ao_async_byte('\r');
+	ao_async_byte('\n');
+}
+
 void
 ao_log_micro_dump(void)
 {
@@ -56,13 +96,26 @@ ao_log_micro_dump(void)
 	uint16_t	nbytes;
 	uint8_t		byte;
 	uint16_t	b;
+	uint16_t	crc = 0xffff;
 
 	ao_eeprom_read(N_SAMPLES_OFFSET, &n_samples, sizeof (n_samples));
+	if (n_samples == 0xffff)
+		n_samples = 0;
 	nbytes = STARTING_LOG_OFFSET + sizeof (uint16_t) * n_samples;
+	ao_async_start();
 	ao_async_byte('M');
 	ao_async_byte('P');
 	for (b = 0; b < nbytes; b++) {
+		if ((b & 0xf) == 0)
+			ao_log_newline();
 		ao_eeprom_read(b, &byte, 1);
-		ao_async_byte(byte);
+		ao_log_hex(byte);
+		crc = ao_log_micro_crc(crc, byte);
 	}
+	ao_log_newline();
+	crc = ~crc;
+	ao_log_hex(crc >> 8);
+	ao_log_hex(crc);
+	ao_log_newline();
+	ao_async_stop();
 }