Make changes suggested in #32.

1. use writenum() for serial number.
2. Add comment and VID checking for SWD programmer delay for Metro M0.
Also:
3. Make warnings be errors on compile so they don't fly by; fix remaining warnings.
4. `make all-boards` now stops when a board fails to build.
5. Fix .binfo location for Metro M4: M4 code is now >8K. Use <n>K constants instead of hex constants for readability.

Makefile

@@ -9,7 +9,7 @@ ifeq ($(CHIP_FAMILY), samd51)
 COMMON_FLAGS = -mthumb -mcpu=cortex-m4 -O2 -g -DSAMD51
 endif
 WFLAGS = \
--Wall -Wstrict-prototypes \
+-Werror -Wall -Wstrict-prototypes \
 -Werror-implicit-function-declaration -Wpointer-arith -std=gnu99 \
 -ffunction-sections -fdata-sections -Wchar-subscripts -Wcomment -Wformat=2 \
 -Wimplicit-int -Wmain -Wparentheses -Wsequence-point -Wreturn-type -Wswitch \
@@ -175,6 +175,6 @@ drop-pkg:
 	rm -rf build/uf2-samd21-$(UF2_VERSION_BASE)
 
 all-boards:
-	for f in `cd boards; ls` ; do "$(MAKE)" BOARD=$$f drop-board ; done
+	for f in `cd boards; ls` ; do "$(MAKE)" BOARD=$$f drop-board || break; done
 
 drop: all-boards drop-pkg

scripts/samd51j19a.ld

@@ -35,12 +35,12 @@ SEARCH_DIR(.)
 /* Memory Spaces Definitions */
 MEMORY
 {
-  rom      (rx)  : ORIGIN = 0x00000000, LENGTH = 0x00080000
-  ram      (rwx) : ORIGIN = 0x20000000, LENGTH = 0x00030000
+  rom      (rx)  : ORIGIN = 0x00000000, LENGTH = 16K
+  ram      (rwx) : ORIGIN = 0x20000000, LENGTH = 192K
 }
 
 /* The stack size used by the application. NOTE: you need to adjust according to your application. */
-STACK_SIZE = DEFINED(STACK_SIZE) ? STACK_SIZE : DEFINED(__stack_size__) ? __stack_size__ : 0xC000;
+STACK_SIZE = DEFINED(STACK_SIZE) ? STACK_SIZE : DEFINED(__stack_size__) ? __stack_size__ : 48K;
 
 /* Section Definitions */
 SECTIONS
@@ -144,7 +144,7 @@ SECTIONS
     . = ALIGN(4);
     _end = . ;
 
-    _binfo_start = 0x00002000 - 4 * 4;
+    _binfo_start = 16K - 4 * 4;
     .binfo _binfo_start : {
       KEEP(*(.binfo)) ;
     } > rom

src/cdc_enumerate.c

@@ -390,15 +390,8 @@ static void load_serial_number(char serial_number[SERIAL_NUMBER_LENGTH]) {
     #endif
     uint32_t serial_number_idx = 0;
     for (int i = 0; i < 4; i++) {
-        uint32_t word = *(addresses[i]);
-        for (int j = 0; j < 8; j++) {
-            // Get top 4 bits.
-            uint8_t nibble = word >> 28;
-            word <<= 4;
-            serial_number[serial_number_idx++] = (nibble >= 10) ? 'A' + (nibble - 10) : '0' + nibble;
-        }
+        serial_number_idx += writeNum(&(serial_number[serial_number_idx]), *(addresses[i]), true);
     }
-
     serial_number[serial_number_idx] = '\0';
 }
 

src/flash_samd51.c

@@ -77,6 +77,8 @@ bool row_same[FLASH_SIZE / NVMCTRL_BLOCK_SIZE][NVMCTRL_BLOCK_SIZE / FLASH_ROW_SI
 #define QUICK_FLASH 1
 
 void flash_write_row(uint32_t *dst, uint32_t *src) {
+    const uint32_t FLASH_ROW_SIZE_WORDS = FLASH_ROW_SIZE / 4;
+
     // The cache in Rev A isn't reliable when reading and writing to the NVM.
     NVMCTRL->CTRLA.bit.CACHEDIS0 = true;
     NVMCTRL->CTRLA.bit.CACHEDIS1 = true;
@@ -85,7 +87,7 @@ void flash_write_row(uint32_t *dst, uint32_t *src) {
     uint8_t row = (((uint32_t) dst) % NVMCTRL_BLOCK_SIZE) / FLASH_ROW_SIZE;
 #if QUICK_FLASH
     bool src_different = false;
-    for (uint32_t i = 0; i < FLASH_ROW_SIZE / 4; ++i) {
+    for (uint32_t i = 0; i < FLASH_ROW_SIZE_WORDS; ++i) {
         if (src[i] != dst[i]) {
             src_different = true;
             break;
@@ -102,17 +104,17 @@ void flash_write_row(uint32_t *dst, uint32_t *src) {
 
     if (!block_erased[block]) {
         uint8_t rows_per_block = NVMCTRL_BLOCK_SIZE / FLASH_ROW_SIZE;
-        uint8_t* block_address = block * NVMCTRL_BLOCK_SIZE;
+        uint32_t* block_address = (uint32_t *) (block * NVMCTRL_BLOCK_SIZE);
 
         bool some_rows_same = false;
         for (uint8_t i = 0; i < rows_per_block; i++) {
             some_rows_same = some_rows_same || row_same[block][i];
         }
-        uint32_t row_cache[rows_per_block][FLASH_ROW_SIZE / 4];
+        uint32_t row_cache[rows_per_block][FLASH_ROW_SIZE_WORDS];
         if (some_rows_same) {
             for (uint8_t i = 0; i < rows_per_block; i++) {
                 if(row_same[block][i]) {
-                    memcpy(row_cache[i], block_address + i * FLASH_ROW_SIZE, FLASH_ROW_SIZE);
+                    memcpy(row_cache[i], block_address + i * FLASH_ROW_SIZE_WORDS, FLASH_ROW_SIZE);
                 }
             }
         }
@@ -123,13 +125,13 @@ void flash_write_row(uint32_t *dst, uint32_t *src) {
                 if(row_same[block][i]) {
                     // dst is a uint32_t pointer so we add the number of words,
                     // not bytes.
-                    flash_write_words(block_address + i * FLASH_ROW_SIZE, row_cache[i], FLASH_ROW_SIZE / 4);
+                    flash_write_words(block_address + i * FLASH_ROW_SIZE_WORDS, row_cache[i], FLASH_ROW_SIZE_WORDS);
                 }
             }
         }
     }
 
-    flash_write_words(dst, src, FLASH_ROW_SIZE / 4);
+    flash_write_words(dst, src, FLASH_ROW_SIZE_WORDS);
 
     // Don't return until we're done writing in case something after us causes
     // a reset.

src/main.c

@@ -162,7 +162,8 @@ int main(void) {
         while (1) {
         }
 
-#if USB_PID == 0x0013  // Metro m0
+#if (USB_VID == 0x239a) && (USB_PID == 0x0013)  // Adafruit Metro M0
+    // Delay a bit so SWD programmer can have time to attach.
     delay(100);
 #endif
     led_init();

src/usart_sam_ba.c

@@ -56,7 +56,6 @@ uint8_t mode_of_transfer;
  * \brief Open the given USART
  */
 void usart_open() {
-    uint32_t inst;
     uint32_t port;
     uint8_t pin;
 
@@ -103,7 +102,7 @@ void usart_open() {
     }
 
     #ifdef SAMD21
-    inst = uart_get_sercom_index(BOOT_USART_MODULE);
+    uint32_t inst = uart_get_sercom_index(BOOT_USART_MODULE);
     /* Enable clock for BOOT_USART_MODULE */
     PM->APBCMASK.reg |= (1u << (inst + PM_APBCMASK_SERCOM0_Pos));