General code cleanup.

2 files changed, 111 insertions, 91 deletions

diff --git a/apps/hott_telemetry/hott_telemetry_main.c b/apps/hott_telemetry/hott_telemetry_main.c
index c5932baeb..00b8f8d66 100644
--- a/apps/hott_telemetry/hott_telemetry_main.c
+++ b/apps/hott_telemetry/hott_telemetry_main.c
@@ -39,6 +39,15 @@
  *
  * The HoTT receiver polls each device at a regular interval at which point
  * a data packet can be returned if necessary.
+ *
+ * NOTE: Since HoTT telemetry works half-duplex over a single wire the wire
+ * is connected to both the UART TX and RX port. In order to send and receive
+ * we need to be able to disable one of these ports at a time. This level of
+ * control is currently not provided by Nuttx (yet) so we need to do this 
+ * at the hardware level for now.
+ *
+ * TODO: Add support for at least the vario and GPS sensors.  
+ *
  */
 
 #include <fcntl.h>
@@ -53,7 +62,7 @@
 
 #include "messages.h"
 
-// The following are equired for UART direct manipulation.
+/* The following are equired for UART direct manipulation. */
 #include <arch/board/board.h>
 #include "up_arch.h"
 #include "chip.h"
@@ -62,7 +71,7 @@
 static int thread_should_exit = false;		/**< Deamon exit flag */
 static int thread_running = false;		/**< Deamon status flag */
 static int deamon_task;				/**< Handle of deamon task / thread */
-
+static uint32_t uart_addr;			/**< The regsitry address of the UART for direct access */
 /**
  * Deamon management function.
  */
@@ -77,6 +86,7 @@ static int read_data(int uart);
 static int send_data(int uart, const struct eam_module_msg *msg);
 static void uart_disable_rx(void);
 static void uart_disable_tx(void);
+static uint32_t get_uart_address(const char *device);
 
 static int open_uart(const char *uart_name, struct termios *uart_config_original)
 {
@@ -125,14 +135,100 @@ static int open_uart(const char *uart_name, struct termios *uart_config_original
 	return uart;
 }
 
+int read_data(int uart)
+{
+        uart_disable_tx();
+
+	const int timeout = 1000;
+	struct pollfd fds[] = { { .fd = uart, .events = POLLIN } };
+
+	if (poll(fds, 1, timeout) > 0) {
+		/* get the mode: binary or text  */
+		char mode;
+		read(uart, &mode, 1);
+		
+		/* read the poll ID (device ID being targetted) */
+		char id;
+		read(uart, &id, 1);
+
+		/* if we have a binary mode request for our sensor ID let's run with it. */
+		if (mode != BINARY_MODE_REQUEST_ID || id != ELECTRIC_AIR_MODULE) {
+			return ERROR;	// not really an error, rather uninteresting.
+		}
+	} else {
+		printf("Timeout\n");
+		return ERROR;
+	}
+	return OK;
+}
+
+int send_data(int uart, const struct eam_module_msg *msg)
+{
+	usleep(POST_READ_DELAY_IN_USECS);
+
+	uart_disable_rx();
+
+	uint16_t checksum = 0;
+  	int size = sizeof(*msg);
+  	char buffer[size];
+
+	memcpy(buffer, msg, size);
+
+	for(int i = 0; i < size; i++) {
+		if (i == size - 1) {
+			/* Set the checksum: the first uint8_t is taken as the checksum. */
+			buffer[i] = checksum & 0xff;
+		} else {
+			checksum += buffer[i];
+		}
+
+		write(uart, &buffer[i], 1);
+		
+		/* Sleep before sending the next byte. */
+		usleep(POST_WRITE_DELAY_IN_USECS);
+	}
+
+	return OK;
+}
+
+void uart_disable_rx(void)
+{
+	uint32_t cr;
+	cr  = getreg32(uart_addr);
+	cr &= ~(USART_CR1_RE);	// turn off RX
+	cr |= (USART_CR1_TE);	// turn on TX
+        putreg32(cr, uart_addr);
+}
+
+void uart_disable_tx(void)
+{
+	uint32_t cr;
+	cr  = getreg32(uart_addr);
+	cr |= (USART_CR1_RE);	// turn on RX
+	cr &= ~(USART_CR1_TE);	// turn off TX
+        putreg32(cr, uart_addr);
+}
+
+uint32_t get_uart_address(const char *device)
+{
+	/* Map the tty device number to the UART address */
+	switch(device[strlen(device) - 1]) {
+		case '0':  return STM32_USART1_CR1;
+		case '1':  return STM32_USART2_CR1;
+		case '2':  return STM32_UART5_CR1;
+		case '3':  return STM32_USART6_CR1;
+		default:   return STM32_UART5_CR1; 
+	}	
+}
+
 int hott_telemetry_thread_main(int argc, char *argv[]) 
 {
 	printf("[hott_telemetry] starting\n");
 
 	thread_running = true;
 
-	char *device = "/dev/ttyS2";  // UART5
 	char *commandline_usage = "\tusage: hott_telemetry start|status|stop [-d device]\n";
+	char *device = "/dev/ttyS2";		/**< Default telemetry port: UART5 */
 
 	/* read commandline arguments */
 	for (int i = 0; i < argc && argv[i]; i++) {
@@ -157,6 +253,11 @@ int hott_telemetry_thread_main(int argc, char *argv[])
 		exit(ERROR);
 	}
 
+	/* Since we need to enable/disable both TX and RX on the UART at the device level
+	 * we need to know the register address of the UART we are working with. Making it
+	 * global so it's easy to remove later when TX/RX control is provided by Nuttx. */
+	uart_addr = get_uart_address(device);
+
 	messages_init();
 
 	struct eam_module_msg msg;
@@ -169,7 +270,6 @@ int hott_telemetry_thread_main(int argc, char *argv[])
 
 	printf("[hott_telemetry] exiting.\n");
 
-	/* close uarts */
 	close(uart);
 
 	thread_running = false;
@@ -187,12 +287,7 @@ usage(const char *reason)
 }
 
 /**
- * The deamon app only briefly exists to start
- * the background job. The stack size assigned in the
- * Makefile does only apply to this management task.
- * 
- * The actual stack size should be set in the call
- * to task_create().
+ * Process command line arguments and tart the daemon.
  */
 int hott_telemetry_main(int argc, char *argv[])
 {
@@ -210,7 +305,7 @@ int hott_telemetry_main(int argc, char *argv[])
 		thread_should_exit = false;
 		deamon_task = task_spawn("hott_telemetry",
 					 SCHED_DEFAULT,
-					 SCHED_PRIORITY_MAX - 20,
+					 SCHED_PRIORITY_MAX - 40,
 					 2048,
 					 hott_telemetry_thread_main,
 					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
@@ -235,81 +330,5 @@ int hott_telemetry_main(int argc, char *argv[])
 	exit(1);
 }
 
-int read_data(int uart)
-{
-        uart_disable_tx();
-
-	const int timeout = 1000;
-	struct pollfd fds[] = { { .fd = uart, .events = POLLIN } };
-
-	if (poll(fds, 1, timeout) > 0) {
-		// get the mode: binary or text
-		char mode;
-		read(uart, &mode, 1);
-		
-		// read the poll ID (device ID being targetted)
-		char id;
-		read(uart, &id, 1);
-
-		//printf("Reading: mode='%x' id='%x'\n", mode, id);
-
-		// if we have a binary mode request for our sensor ID let's run with it
-		if (mode != BINARY_MODE_REQUEST_ID || id != ELECTRIC_AIR_MODULE) {
-			return ERROR;	// not really an error, rather uninteresting.
-		}
-	} else {
-		printf("Timeout\n");
-		return ERROR;
-	}
-	return OK;
-}
-
-int send_data(int uart, const struct eam_module_msg *msg)
-{
-	usleep(POST_READ_DELAY_IN_USECS);
-
-	uart_disable_rx();
-
-	uint16_t checksum = 0;
-  	int size = sizeof(*msg);
-  	char buffer[size];
-
-	memcpy(buffer, msg, size);
-
-	for(int i = 0; i < size; i++) {
-		if (i == size - 1) {
-			// Set the checksum: the first uint8_t is taken as the checksum.
-			buffer[i] = checksum & 0xff;
-		} else {
-			checksum += buffer[i];
-		}
-
-		//printf("%x ", buffer[i]);
-		write(uart, &buffer[i], 1);
-		
-		// Sleep before sending the next uint8_t.
-		usleep(POST_WRITE_DELAY_IN_USECS);
-	}
-
-	return OK;
-}
-
-void uart_disable_rx()
-{
-	uint32_t cr;
-	cr  = getreg32(STM32_UART5_CR1);
-	cr &= ~(USART_CR1_RE);	// turn off RX
-	cr |= (USART_CR1_TE);	// turn on TX
-        putreg32(cr, STM32_UART5_CR1);
-}
-
-void uart_disable_tx()
-{
-	uint32_t cr;
-	cr  = getreg32(STM32_UART5_CR1);
-	cr |= (USART_CR1_RE);	// turn on RX
-	cr &= ~(USART_CR1_TE);	// turn off TX
-        putreg32(cr, STM32_UART5_CR1);
-}
 
 
diff --git a/apps/hott_telemetry/messages.h b/apps/hott_telemetry/messages.h
index 562010a06..fb305cd8d 100644
--- a/apps/hott_telemetry/messages.h
+++ b/apps/hott_telemetry/messages.h
@@ -43,10 +43,10 @@
 
 #include <stdlib.h>
 
-// The HoTT receiver demands a minimum 5ms period of silence after delivering its request. 
+/* The HoTT receiver demands a minimum 5ms period of silence after delivering its request. */
 #define POST_READ_DELAY_IN_USECS	4500 
-// A pause of 3ms is required between each uint8_t sent back to the HoTT receiver. Much lower
-// values can be used in practise though.
+/* A pause of 3ms is required between each uint8_t sent back to the HoTT receiver. Much lower
+   values can be used in practise though. */
 #define POST_WRITE_DELAY_IN_USECS	1500
 
 // Protocol constants.
@@ -55,10 +55,11 @@
 #define STOP_BYTE		0x7d
 #define TEMP_ZERO_CELSIUS	0x14
 
-// Electric Air Module (EAM) constants.
+/* Electric Air Module (EAM) constants. */
 #define ELECTRIC_AIR_MODULE	0x8e
 #define EAM_SENSOR_ID		0xe0
 
+/* The Electric Air Module message. */
 struct eam_module_msg {
 	uint8_t start;			/**< Start byte   				*/
 	uint8_t eam_sensor_id;		/**< EAM sensor ID 				*/