From 6afccfdb827fe3169f4efafd8c78a1ede2964851 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Wed, 14 Feb 2018 12:35:23 +0100
Subject: [PATCH] BV HiZ: add RS-485 self-test

---
 lib/busvoodoo_hiz.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/lib/busvoodoo_hiz.c b/lib/busvoodoo_hiz.c
index 687d591..211e338 100644
--- a/lib/busvoodoo_hiz.c
+++ b/lib/busvoodoo_hiz.c
@@ -280,6 +280,7 @@ static bool busvoodoo_hiz_test_self(void)
 #endif
 		}
 	}
+
 	// pull all pins up and ensure they are high
 	for (uint8_t pin=0; pin<LENGTH(busvoodoo_io_ports) && pin<LENGTH(busvoodoo_io_pins); pin++) {
 		gpio_set_mode(busvoodoo_io_ports[pin], GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, busvoodoo_io_pins[pin]); // set pin to input
@@ -423,6 +424,44 @@ static bool busvoodoo_hiz_test_self(void)
 	busvoodoo_lv_set(0); // disable LV voltage regulator
 	busvoodoo_embedded_pullup(false); // disable pull-ups
 
+	// test RS-485 transceiver
+	if (busvoodoo_full) {
+		// configure transceiver
+		gpio_set(GPIO(BUSVOODOO_RS485_DE_PORT), GPIO(BUSVOODOO_RS485_DE_PIN)); // enable transmitter
+		gpio_clear(GPIO(BUSVOODOO_RS485_RE_PORT), GPIO(BUSVOODOO_RS485_RE_PIN)); // enable receiver
+		gpio_set_mode(GPIO(BUSVOODOO_RS485_TX_PORT), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(BUSVOODOO_RS485_TX_PIN)); // set TX as output
+		gpio_set_mode(GPIO(BUSVOODOO_RS485_RX_PORT), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO(BUSVOODOO_RS485_RX_PIN)); // set RX as input with pull up/down
+		// test high signal
+		gpio_set(GPIO(BUSVOODOO_RS485_RX_PORT), GPIO(BUSVOODOO_RS485_RX_PIN)); // pull RX up
+		gpio_clear(GPIO(BUSVOODOO_RS485_TX_PORT), GPIO(BUSVOODOO_RS485_TX_PIN)); // set TX low
+		sleep_us(100); // let voltage settle
+		if (gpio_get(GPIO(BUSVOODOO_RS485_RX_PORT), GPIO(BUSVOODOO_RS485_RX_PIN))) { // test if RX is still high
+			printf("RS-485 RX is high while TX is set low\n"); // warn user about the error
+#if DEBUG
+			while (true);
+#else
+			goto error;
+#endif
+		}
+		// test low signal
+		gpio_clear(GPIO(BUSVOODOO_RS485_RX_PORT), GPIO(BUSVOODOO_RS485_RX_PIN)); // pull RX down
+		gpio_set(GPIO(BUSVOODOO_RS485_TX_PORT), GPIO(BUSVOODOO_RS485_TX_PIN)); // set TX high
+		sleep_us(100); // let voltage settle
+		if (0==gpio_get(GPIO(BUSVOODOO_RS485_RX_PORT), GPIO(BUSVOODOO_RS485_RX_PIN))) { // test if RX is still low
+			printf("RS-485 RX is low while TX is set high\n"); // warn user about the error
+#if DEBUG
+			while (true);
+#else
+			goto error;
+#endif
+		}
+		// release transceiver
+		gpio_set(GPIO(BUSVOODOO_RS485_RE_PORT), GPIO(BUSVOODOO_RS485_RE_PIN)); // set high to disable receiver
+		gpio_clear(GPIO(BUSVOODOO_RS485_DE_PORT), GPIO(BUSVOODOO_RS485_DE_PIN)); // set low to disable transmitter
+		gpio_set_mode(GPIO(BUSVOODOO_RS485_TX_PORT), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO(BUSVOODOO_RS485_TX_PIN)); // set pin to floating
+		gpio_set_mode(GPIO(BUSVOODOO_RS485_RX_PORT), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO(BUSVOODOO_RS485_RX_PIN)); // set pin to floating
+	}
+
 	to_return = true; // all tests are successful
 #if DEBUG
 #else