Enable REPL over USB.

All of the code was there except the linker was failing to clear the bss section because I added too many .zeros. The should have only been the exported globals that start with _ like _szero = .. Fixing that and turn on the usb transmit fixed everything.

Author: tannewt

atmel-samd/README.md

@@ -7,11 +7,13 @@ M0 BLE.
 ## Building
 
 The Makefile has the ability to build for a SAMD21x18, and by default
-includes some start-up code and also enables a UART for communication.  To build:
+includes some start-up code and also enables a UART for communication.  To
+build:
 
     make CROSS=1
 
-It will build for the Arduino Zero by default. You may change it by setting `BOARD`. For example:
+It will build for the Arduino Zero by default. You may change it by setting
+`BOARD`. For example:
 
     make CROSS=1 BOARD=feather_m0_ble
 
@@ -20,14 +22,17 @@ Board names are the directory names in the `boards` folder.
 ## Deploying
 
 ### Arduino Bootloader
-If your board has an existing Arduino bootloader on it then you can use bossac to flash MicroPython. After building run:
+If your board has an existing Arduino bootloader on it then you can use bossac
+to flash MicroPython. After building run:
 
     tools/bossac_osx -e -w -v -b build-feather_m0_ble/firmware.bin
 
 ### No Bootloader via GDB
-This method works for loading MicroPython onto the Arduino Zero via the programming port rather than the native USB port.
+This method works for loading MicroPython onto the Arduino Zero via the
+programming port rather than the native USB port.
 
-Note: These instructions are tested on Mac OSX and will vary for different platforms.
+Note: These instructions are tested on Mac OSX and will vary for different
+platforms.
 
     openocd -f ~/Library/Arduino15/packages/arduino/hardware/samd/1.6.6/variants/arduino_zero/openocd_scripts/arduino_zero.cfg
 
@@ -43,8 +48,10 @@ In another terminal from `micropython/atmel-samd`:
     (gdb) continue
 
 ## Connecting
-The current Atmel SAMD implementation only works over UART. To connect to it from OSX do something like this:
+All boards are currently configured to work over USB rather than UART. To
+connect to it from OSX do something like this:
 
     screen /dev/tty.usbmodem142422 115200
 
-You may not see a prompt immediately because it doesn't know you connected. To get one either hit enter to get `>>>` or do CTRL-B to get the full header.
+You may not see a prompt immediately because it doesn't know you connected. To
+get one either hit enter to get `>>>` or do CTRL-B to get the full header.

atmel-samd/boards/arduino_zero/mpconfigboard.h

@@ -1,7 +1,7 @@
 // LEDs
 #define MICROPY_HW_LED1              PIN_PA17 // red
-#define UART_REPL
-// #define USB_REPL
+// #define UART_REPL
+#define USB_REPL
 
 #define MICROPY_HW_BOARD_NAME "Arduino Zero"
 #define MICROPY_HW_MCU_NAME "samd21g18"

atmel-samd/boards/samd21x18-bootloader.ld

@@ -40,6 +40,8 @@ SECTIONS
     {
         . = ALIGN(4);
         _srelocate = .;        /* create a global symbol at data start; used by startup code in order to initialise the .data section in RAM */
+        *(.ramfunc)
+        *(.ramfunc*)
         *(.data)           /* .data sections */
         *(.data*)          /* .data* sections */
 
@@ -48,28 +50,18 @@ SECTIONS
     } >RAM
 
     /* Uninitialized data section */
-    .ramfunc :
-    {
-        . = ALIGN(4);
-        _sramfunc = .;         /* define a global symbol at ramfunc start; used by startup code */
-        *(.ramfunc)
-        *(.ramfunc*)
-
-        . = ALIGN(4);
-        _eramfunc = .;         /* define a global symbol at ramfunc end; used by startup code */
-    } >RAM
-
-    /* Uninitialized data section */
-    .zero :
+    .bss :
     {
         . = ALIGN(4);
+        _sbss = .;
         _szero = .;         /* define a global symbol at bss start; used by startup code */
-        *(.zero)
-        *(.zero*)
+        *(.bss)
+        *(.bss*)
         *(COMMON)
 
         . = ALIGN(4);
         _ezero = .;         /* define a global symbol at bss end; used by startup code */
+        _ebss = .;
     } >RAM
 
     .ARM.attributes 0 : { *(.ARM.attributes) }

atmel-samd/boards/samd21x18.ld

@@ -28,10 +28,9 @@ SECTIONS
 
         . = ALIGN(4);
         _etext = .;        /* define a global symbol at end of code */
-        _sidata = _etext;  /* This is used by the startup in order to initialize the .data secion */
+        _sidata = _etext;  /* This is used by the startup in order to initialize the .data section */
     } >FLASH
 
-
     /* This is the initialized data section
     The program executes knowing that the data is in the RAM
     but the loader puts the initial values in the FLASH (inidata).
@@ -40,6 +39,8 @@ SECTIONS
     {
         . = ALIGN(4);
         _srelocate = .;        /* create a global symbol at data start; used by startup code in order to initialise the .data section in RAM */
+        *(.ramfunc)
+        *(.ramfunc*)
         *(.data)           /* .data sections */
         *(.data*)          /* .data* sections */
 
@@ -48,28 +49,18 @@ SECTIONS
     } >RAM
 
     /* Uninitialized data section */
-    .ramfunc :
-    {
-        . = ALIGN(4);
-        _sramfunc = .;         /* define a global symbol at ramfunc start; used by startup code */
-        *(.ramfunc)
-        *(.ramfunc*)
-
-        . = ALIGN(4);
-        _eramfunc = .;         /* define a global symbol at ramfunc end; used by startup code */
-    } >RAM
-
-    /* Uninitialized data section */
-    .zero :
+    .bss :
     {
         . = ALIGN(4);
+        _sbss = .;
         _szero = .;         /* define a global symbol at bss start; used by startup code */
-        *(.zero)
-        *(.zero*)
+        *(.bss)
+        *(.bss*)
         *(COMMON)
 
         . = ALIGN(4);
         _ezero = .;         /* define a global symbol at bss end; used by startup code */
+        _ebss = .;
     } >RAM
 
     .ARM.attributes 0 : { *(.ARM.attributes) }

atmel-samd/main.c

@@ -127,35 +127,22 @@ void samd21_init(void) {
 
   delay_init();
 
-  struct port_config pin_conf;
-  port_get_config_defaults(&pin_conf);
-
-  pin_conf.direction  = PORT_PIN_DIR_OUTPUT;
-  port_pin_set_config(MICROPY_HW_LED1, &pin_conf);
-  port_pin_set_output_level(MICROPY_HW_LED1, false);
-
-  // Start USB stack to authorize VBus monitoring
-  for (int i = 0; i < 10; i++) {
-    port_pin_toggle_output_level(MICROPY_HW_LED1);
-    delay_ms(100);
-  }
+  // Uncomment to init PIN_PA17 for debugging.
+  // struct port_config pin_conf;
+  // port_get_config_defaults(&pin_conf);
+  //
+  // pin_conf.direction  = PORT_PIN_DIR_OUTPUT;
+  // port_pin_set_config(MICROPY_HW_LED1, &pin_conf);
+  // port_pin_set_output_level(MICROPY_HW_LED1, false);
+
   #ifdef USB_REPL
     udc_start();
   #endif
-  for (int i = 0; i < 10; i++) {
-    port_pin_toggle_output_level(MICROPY_HW_LED1);
-    delay_ms(200);
-  }
 
   // TODO(tannewt): Switch to proper pyb based UARTs.
   #ifdef UART_REPL
     configure_usart();
   #endif
-  for (int i = 0; i < 10; i++) {
-    port_pin_toggle_output_level(MICROPY_HW_LED1);
-    delay_ms(500);
-  }
-
 }
 
 #endif

atmel-samd/mphalport.c

@@ -27,7 +27,7 @@ int mp_hal_stdin_rx_chr(void) {
   for (;;) {
     #ifdef USB_REPL
     if (mp_cdc_enabled && udi_cdc_is_rx_ready()) {
-     return udi_cdc_getc();
+      return udi_cdc_getc();
     }
     #endif
     #ifdef UART_REPL
@@ -47,10 +47,15 @@ int mp_hal_stdin_rx_chr(void) {
 //}
 
 void mp_hal_stdout_tx_strn(const char *str, size_t len) {
+  #ifdef UART_REPL
   usart_write_buffer_wait(&usart_instance, (uint8_t*) str, len);
-  // if (mp_cdc_enabled && udi_cdc_is_tx_ready()) {
-  //   udi_cdc_write_buf(str, len);
-  // }
+  #endif
+
+  #ifdef USB_REPL
+  if (mp_cdc_enabled && udi_cdc_is_tx_ready()) {
+    udi_cdc_write_buf(str, len);
+  }
+  #endif
 }
 
 //void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {