Add some helpful logging and print utilities

firmware/src/main.cpp

@@ -36,13 +36,17 @@ void setup()
   Serial.print("Connected! IP Address: ");
   Serial.println(WiFi.localIP());
 
-  fetchAndDrawImage();
+  // fetchAndDrawImage(clearImage);
+  // fetchAndDrawImage(calibrationImage);
+  fetchAndDrawImage(fetchImage);
+
+  hibernate_and_restart();
 }
 
-void fetchAndDrawImage() {
+void fetchAndDrawImage(const char* url) {
   HTTPClient http;
 
-  http.begin(serverName);
+  http.begin(url);
   http.setTimeout(40000); // wait up to 40 seconds for response
   http.setAuthorization("username", "password");
   http.addHeader("Content-Type", "application/json");
@@ -65,12 +69,13 @@ void fetchAndDrawImage() {
   }
 
   http.end();
-
-  hibernate_and_restart();
 }
 
 void hibernate_and_restart() {
   // Go to sleep and wake up later
+  Serial.print("Begining hibernation. Waking up in ");
+  Serial.print(HIBERNATE_TIME_SEC);
+  Serial.println(" seconds");
 
   // Configure wake up source as timer
   esp_sleep_enable_timer_wakeup(HIBERNATE_TIME_SEC * 1000000);

server/einkimage.go

@@ -103,6 +103,22 @@ func GenerateCalibrationImage(width, height int, colorSpace ColorSpace) []byte {
 	return packBytesIntoNibbles(einkImage)
 }
 
+func GenerateClearImage(width, height int, colorSpace ColorSpace) []byte {
+	var einkImage []byte
+
+	// Assume the first color is white
+	// What really matters is that the color is the same for the enitre image
+	clearIndex := 3
+
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			einkImage = append(einkImage, colorSpace[clearIndex].Code)
+		}
+	}
+
+	return packBytesIntoNibbles(einkImage)
+}
+
 func packBytesIntoNibbles(input []byte) []byte {
 	// input length must divisible by 2
 

server/main.go

@@ -68,6 +68,22 @@ func calibrationImage(w http.ResponseWriter, r *http.Request) {
 	w.Write(data)
 }
 
+func clearImage(w http.ResponseWriter, r *http.Request) {
+	var imageProps ImageProperties
+	err := json.NewDecoder(r.Body).Decode(&imageProps)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	data := GenerateClearImage(imageProps.Width, imageProps.Height, imageProps.ColorSpace)
+
+	fmt.Printf("Bytes to send: %+v\n", len(data))
+
+	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
+	w.Write(data)
+}
+
 func fetchImage(w http.ResponseWriter, r *http.Request) {
 	var imageProps ImageProperties
 	err := json.NewDecoder(r.Body).Decode(&imageProps)
@@ -130,6 +146,7 @@ func main() {
 		// r.Use(basicAuth)
 		r.Post("/fetchImage", fetchImage)
 		r.Post("/calibrationImage", calibrationImage)
+		r.Post("/clearImage", clearImage)
 	})
 
 	fmt.Println("Started server")