Improved stability of the ESP32 driver

sifive_software/src/esp32.c

@@ -116,6 +116,7 @@ enum esp32_result esp32_recv(void) {
 // Checks whether the expected value and length was received, without performing a new receive operation.
 enum esp32_result esp32_check_expectation(int how, const char *expected_value, uint32_t expected_len) {
 	if(strncmp(expected_value, recv_buf, min(expected_len, recv_len)) != 0 || recv_len != expected_len) {
+#if VERBOSITY > 0
 		if(how == EXPECT_NOISY) {
 			printf("Got an unexpected reply from ESP32:\r\n");
 
@@ -140,10 +141,13 @@ enum esp32_result esp32_check_expectation(int how, const char *expected_value, u
 			}
 			if(recv_buf[0] == '\r' && recv_buf[1] == '\n') {
 				printf("  Data (string):     \\r\\n%s\r\n", &recv_buf[2]);
+			} else if(recv_len == 0) {
+				printf("  Data (string):     <no data>\r\n");
 			} else {
 				printf("  Data (string):     %s\r\n", recv_buf);
 			}
 		}
+#endif
 
 		return ESP32_ERR;
 	}
@@ -197,33 +201,27 @@ enum esp32_result esp32_connect_to_ap(const char *ssid, const char *pwd) {
 	// Join the AP
 	spi_send(join_msg);
 
-	// Check the result of the command
-	if(esp32_expect("WIFI CONNECTED\r\n", 16) == ESP32_ERR) {
+	// We expect three messages in return if everything goes well:
+	// - WIFI CONNECTED
+	// - WIFI GOT IP
+	// - OK
+	//
+	// These messages take some time to appear however, so we just try receiving messages until they arrive.
+	while(esp32_recv() == ESP32_ERR);
+	if(esp32_check_expectation(EXPECT_NOISY, "WIFI CONNECTED\r\n", 16) == ESP32_ERR) {
 		return ESP32_ERR;
 	}
 
-	// Check the status until we are connected.
-	do {
-		spi_send("AT+CIPSTATUS\r\n");
-		esp32_recv();
-		delay(DELAY);
-	} while(esp32_check_expectation(EXPECT_SILENT, MSG_BUSY) == ESP32_OK ||
-			esp32_check_expectation(EXPECT_SILENT, "ERR CODE:0x010b0000\r\n", 21) == ESP32_OK ||
-			esp32_check_expectation(EXPECT_SILENT, "WIFI GOT IP\r\n", 13) == ESP32_OK);
-
-	// At most one "OK" message can occur here, preceding the status
-	while(esp32_check_expectation(EXPECT_SILENT, MSG_OK) == ESP32_OK) {
-		esp32_recv();
+	while(esp32_recv() == ESP32_ERR);
+	if(esp32_check_expectation(EXPECT_NOISY, "WIFI GOT IP\r\n", 13) == ESP32_ERR) {
+		return ESP32_ERR;
 	}
 
-	// Check the status reports to ensure that we are connected
-	if(esp32_check_expectation(EXPECT_NOISY, "STATUS:2\r\n", 10) == ESP32_ERR) {
+	while(esp32_recv() == ESP32_ERR);
+	if(esp32_check_expectation(EXPECT_NOISY, MSG_OK) == ESP32_ERR) {
 		return ESP32_ERR;
 	}
 
-	// Soak up any extra messages generated by the status requests
-	while(esp32_recv() == ESP32_OK) {}
-
 	return ESP32_OK;
 }
 
@@ -358,7 +356,6 @@ enum esp32_event esp32_wait_for_event(uint32_t *id, uint32_t *len, char **data)
 		return ESP32_CLOSED_CONNECTION;
 	}
 
-
 	if(data != NULL) {
 		*data = buf;
 	}
@@ -384,15 +381,18 @@ enum esp32_result esp32_send(uint32_t id, uint32_t len, char *data) {
 	// Actually send the data
 	spi_send_with_len(data, len);
 
-	esp32_recv();
-	if(strncmp(recv_buf, "\r\nRecv ", 7) != 0) {
-		printf("Unexpected message from the ESP32.\r\n");
-		return ESP32_ERR;
-	}
+	buf_len = 35;
+	char recv_msg_buf[buf_len];
+	snprintf(recv_msg_buf, buf_len, "\r\nRecv %d bytes\r\n", len);
+	esp32_expect(recv_msg_buf, strlen(recv_msg_buf));
 
-	if(esp32_expect("\r\nSEND OK\r\n", 11) == ESP32_ERR) {
+	// Usually the ESP32 will send a SEND OK message here, but there appear to be some situations in which
+	// that message is not sent, so we check it here, but don't error if it doesn't exist.
+	if(esp32_recv() == ESP32_OK) {
+		if(esp32_check_expectation(EXPECT_NOISY, "\r\nSEND OK\r\n", 11) == ESP32_ERR) {
 			return ESP32_ERR;
 		}
+	}
 
 	return ESP32_OK;
 }
@@ -404,9 +404,18 @@ enum esp32_result esp32_close_connection(uint32_t id) {
 	snprintf(send_msg, buf_len, "AT+CIPCLOSE=%d\r\n", id);
 	spi_send(send_msg);
 
-	if(esp32_expect(MSG_OK) == ESP32_ERR) {
+	// Sometimes the ESP32 sends no message here (but with extreme delay), so we also accept no message.
+	if(esp32_recv() == ESP32_OK) {
+		// After trying it a couple of times, it became apparent that sometimes an error is returned here.
+		// The connection will still appear to be closed on the ESP32 (at least the ID is reused).
+		// This is likely because the other party disconnected first.
+		// Because of this we accept both OK and ERROR messages here.
+		if(esp32_check_expectation(EXPECT_SILENT, MSG_OK) != ESP32_OK && esp32_check_expectation(EXPECT_SILENT, "\r\nERROR\r\n", 9) != ESP32_OK) {
+			// We did not get the expected message, now we just do a noisy comparison to report the error.
+			esp32_check_expectation(EXPECT_NOISY, MSG_OK);
 			return ESP32_ERR;
 		}
+	}
 
 	return ESP32_OK;
 }

sifive_software/src/spi.c

@@ -110,7 +110,9 @@ void spi_init(uint32_t spi_clock)
     // Enable IOF for pin 3,4,5,9 (don't touch other pins)
     IOF_EN |= IOF_SPI_ENABLE;
     
+#if VERBOSITY > 2
     printf("DONE\r\n");
+#endif
 }
 
 //----------------------------------------------------------------------