Add (untested) support for UART output.

.gitignore

@@ -21,6 +21,7 @@
 *.dylib
 
 # Executables
+*.bin
 *.exe
 *.out
 *.app
@@ -31,6 +32,9 @@
 # Debug files
 *.dSYM/
 *.su
+*.d
+*.dump
+*.map
 
 # Tarballs/compressed files
 *.zip

efm32hg-blinky/Makefile

@@ -67,7 +67,6 @@ LFLAGS = -mcpu=cortex-m0plus \
 				 -Wl,--start-group \
 				 -lgcc \
 				 -lc_nano \
-				 -lnosys \
 				 -Wl,--end-group
 
 
@@ -133,7 +132,9 @@ deps:
 GECKO_A_SRC = Gecko_SDK/Device/SiliconLabs/EFM32HG/Source/GCC/startup_efm32hg.S
 GECKO_C_SRC = $(shell find Gecko_SDK/emlib/src -name \*.c) \
 							Gecko_SDK/Device/SiliconLabs/EFM32HG/Source/system_efm32hg.c \
-							Gecko_SDK/kits/common/drivers/capsense.c
+							Gecko_SDK/kits/common/drivers/capsense.c \
+							Gecko_SDK/kits/common/drivers/retargetio.c \
+							Gecko_SDK/kits/common/drivers/retargetserial.c
 GECKO_OBJ = $(patsubst %.S,%.o,$(GECKO_A_SRC)) \
 						$(patsubst %.c,%.o,$(GECKO_C_SRC))
 

efm32hg-blinky/main.c

@@ -12,10 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <stdint.h>
 #include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
 
 #include "capsense.h"
+#include "retargetserial.h"
+
 #include "em_chip.h"
 #include "em_cmu.h"
 #include "em_device.h"
@@ -46,31 +49,43 @@ int main() {
   // errata (implements workarounds, etc).
   CHIP_Init();
 
+  // Initialise the LEUART, and map output from printf() to it.
+  RETARGET_SerialInit();
+  RETARGET_SerialCrLf(1);
+
   // Switch on the clock for GPIO. Even though there's no immediately obvious
   // timing stuff going on beyond the SysTick below, it still needs to be
   // enabled for the GPIO to work.
+  printf("Enabling GPIO clock\n");
   CMU_ClockEnable(cmuClock_GPIO, true);
 
   // Sets up and enable the `SysTick_Handler' interrupt to fire once every 1ms.
   // ref: http://community.silabs.com/t5/Official-Blog-of-Silicon-Labs/Chapter-5-MCU-Clocking-Part-2-The-SysTick-Interrupt/ba-p/145297
+  printf("Starting systick timer\n");
   if (SysTick_Config(CMU_ClockFreqGet(cmuClock_CORE) / 1000)) {
     // Something went wrong.
+    printf("ERROR WHILST INITIALISING SYSTICK TIMER! HALTING.\n");
     while (1);
   }
 
   // Set up two pins with the GPIO controller and configure them to be open
   // drain:
   //  - PA0 == green
   //  - PB7 == red
+  printf("Setting up GPIO pins to be open-drain\n");
   GPIO_PinModeSet(gpioPortA, 0, gpioModeWiredAnd, 0);
   GPIO_PinModeSet(gpioPortB, 7, gpioModeWiredAnd, 0);
 
   // Enable the capacitive touch sensor. Remember, this consumes TIMER0 and
   // TIMER1, so those are off-limits to us.
+  printf("Initialising the capacitive touch sensor\n");
   CAPSENSE_Init();
 
-  // Blink infinitely, in an aviation-like pattern.
+  // Blink infinitely.
+  printf("Beginning application loop.\n");
   while (1) {
+    printf("Hello world\n");
+
     // Clear the PA0 bit, allowing the FET to sink to ground and thus lighting
     // up the green LED.
     GPIO_PinOutClear(gpioPortA, 0);
@@ -102,6 +117,7 @@ int main() {
     // touched, rapid blink the green LED ten times.
     if (CAPSENSE_getPressed(BUTTON0_CHANNEL) &&
         !CAPSENSE_getPressed(BUTTON1_CHANNEL)) {
+      printf("Detected touch near green LED\n");
       int i;
       for (i = 10; i > 0; i--) {
         GPIO_PinOutClear(gpioPortA, 0);
@@ -113,6 +129,7 @@ int main() {
     // touched, rapid blink the red LED ten times.
     } else if (CAPSENSE_getPressed(BUTTON1_CHANNEL) &&
                !CAPSENSE_getPressed(BUTTON0_CHANNEL)) {
+      printf("Detected touch near red LED\n");
       int i;
       for (i = 10; i > 0; i--) {
         GPIO_PinOutClear(gpioPortB, 7);

efm32hg-blinky/retargetserialconfig.h

@@ -0,0 +1,35 @@
+// Copyright 2016 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// This file contains configuration/settings for the Gecko SDK-provided
+// "retargetserial" driver at Gecko_SDK/kits/common/drivers/retargetserial.c.
+
+#ifndef _RETARGETSERIALCONFIG_H
+#define _RETARGETSERIALCONFIG_H
+
+#define RETARGET_CLK      cmuClock_LEUART0
+#define RETARGET_IRQ_NAME LEUART0_IRQHandler
+#define RETARGET_IRQn     LEUART0_IRQn
+#define RETARGET_LEUART   1
+#define RETARGET_LOCATION LEUART_ROUTE_LOCATION_LOC1
+#define RETARGET_PERIPHERAL_ENABLE()
+#define RETARGET_RX       LEUART_Rx
+#define RETARGET_RXPIN    14
+#define RETARGET_RXPORT   gpioPortB
+#define RETARGET_TX       LEUART_Tx
+#define RETARGET_TXPIN    13
+#define RETARGET_TXPORT   gpioPortB
+#define RETARGET_UART     LEUART0
+
+#endif /* _RETARGETSERIALCONFIG_H */