Add Uno communication

2 files changed, 113 insertions, 0 deletions

diff --git a/Venus_Skeleton/comm.c b/Venus_Skeleton/comm.c
new file mode 100644
index 0000000..f5392e0
--- /dev/null
+++ b/Venus_Skeleton/comm.c
@@ -0,0 +1,90 @@
+/**
+ * Serial communication module.
+ */
+
+#include <stdbool.h>
+#include "dataTypes.h"
+
+serial_state_t serial_state = SERIAL_UNKNOWN;
+
+static void handle_recv(int r);
+
+static void handle_ctrl(int r) {
+	// detect reset procedure
+	switch (r) {
+	case RESET1:
+		// reset request received, ack and wait for RESET2
+		Serial.write(ACK1);
+		serial_state = SERIAL_INIT;
+		return;
+	case RESET2:
+		if (serial_state == SERIAL_INIT) {
+			// Handshake completed!
+			Serial.write(ACK2);
+			serial_state = SERIAL_READY;
+		} else {
+			// invalid state, reject it
+			Serial.write(OUTOFSYNC);
+			serial_state = SERIAL_UNKNOWN;
+		}
+		return;
+	case PONG:
+		// TODO mark as alive if PING was previously sent
+		return;
+	}
+	// TODO commands for navigation? Use DATA_LEN, etc?
+}
+
+void handle_serial(data_t *data, int changedBits) {
+	// first attempt sync
+	while (Serial.available()) {
+		r = Serial.read();
+
+		if ((r & 0xC0) == 0x80) {
+			// handle control packets
+			handle_ctrl(r);
+		// TODO if DATA_ESCAPE or DATA_LEN1, react appropriately
+		} else if (serial_state == SERIAL_READY) {
+			// handle normal data only when the handshake has completed.
+			handle_recv(r);
+		}
+	}
+
+	if (serial_state != SERIAL_READY) {
+		// Hardware is not ready, do not send data.
+		return;
+	}
+
+	// then send queued data
+}
+
+// writes data of length len
+static void serial_write_data(const char *data, unsigned len) {
+	len--; // length on wire is one smaller (00 means 1 byte, 01 means 2, etc.)
+	if (len >= 0 && len < 56) {
+		Serial.write(0x80 + len + 7);
+	} else if (len >= 0 && len < 256) {
+		Serial.write(0x88 | (len >> 5));
+		Serial.write(0xA0 | (len & 0x1F));
+	} else {
+		// zero length or too long.
+		return;
+	}
+	// write remainder
+	for (unsigned i = 0; i < len; i++) {
+		char c = data[i];
+		if (c & 0x80) {
+			Serial.write(DATA_ESCAPE);
+			Serial.write(c & ~0x80);
+		} else {
+			Serial.write(c);
+		}
+	}
+}
+
+void serial_print_debug(const char *str) {
+	serial_print_debug(str, strlen(str));
+}
+
+static void handle_recv(int r) {
+}
diff --git a/Venus_Skeleton/comm.h b/Venus_Skeleton/comm.h
new file mode 100644
index 0000000..5cdf77e
--- /dev/null
+++ b/Venus_Skeleton/comm.h
@@ -0,0 +1,23 @@
+typedef enum {
+	RESET1      = 0x81,
+	RESET2      = 0x82,
+	ACK1        = 0x81,
+	ACK2        = 0x82,
+	OUTOFSYNC   = 0x83,
+	PING        = 0x80,
+	PONG        = 0x80,
+	DATA_ESCAPE = 0x84,
+} serial_control_command_t;
+
+typedef enum {
+	// waiting for RESET1
+	SERIAL_UNKNOWN,
+	// received RESET1, sent ACK1, waiting for RESET2
+	SERIAL_INIT,
+	// received RESET2, sent ACK1, waiting for other commands
+	SERIAL_READY,
+} serial_state_t;
+extern serial_state_t serial_state;
+
+void handle_serial(data_t *data, int changedBits);
+void serial_print_debug(const char *str);