From 3791dfa7771421612bc0e3149ca38cb07fa32f1e Mon Sep 17 00:00:00 2001
From: Gregor Riepl <onitake@gmail.com>
Date: Mon, 18 Jan 2021 20:27:20 +0100
Subject: [PATCH] Implement change report on feedback module

---
 feedback/firmware/main.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/feedback/firmware/main.c b/feedback/firmware/main.c
index 8e38607..881b366 100644
--- a/feedback/firmware/main.c
+++ b/feedback/firmware/main.c
@@ -5,6 +5,7 @@
 #include <can.h>
 
 static bool report_change = false;
+static uint16_t saved_status;
 
 static void init() {
 	// Set PB as input, pull-up off
@@ -42,7 +43,7 @@ static void init() {
 	sei();
 }
 
-static void send_status() {
+static uint16_t get_status() {
 	// Get GPIO state
 	// PB -> invert -> Dend..Hend, Dempty..Fempty
 	uint8_t statusl = ~PINB;
@@ -53,6 +54,10 @@ static void send_status() {
 	uint8_t swres = (pinc & _BV(4)) ? _BV(2) : 0;
 	uint8_t statush = gempty | hempty | swres;
 
+	return ((uint16_t) statush << 8) | ((uint16_t) statusl);
+}
+
+static void send_status(uint16_t status) {
 	if (can_check_free_buffer()) {
 		can_t msg = {
 			.id = 0x10,
@@ -60,13 +65,19 @@ static void send_status() {
 				.rtr = 0,
 			},
 			.length = 2,
-			.data = { statush, statusl, },
+			.data = { (uint8_t) (status >> 8), status & 0xff, },
 		};
 		can_send_message(&msg);
 	}
 }
 
 static void loop() {
+	// Check for status changes
+	uint16_t new_status = get_status();
+	if (report_change && new_status != saved_status) {
+		send_status(new_status);
+		saved_status = new_status;
+	}
 	// Check for new messages
 	if (can_check_message()) {
 		can_t msg = { 0 };
@@ -74,7 +85,7 @@ static void loop() {
 		if (status != 0) {
 			switch (msg.id) {
 			case 0x10:
-				send_status();
+				send_status(get_status());
 				break;
 			case 0x4f:
 				if (msg.length == 1) {