那些遇到过的问题

在 atmega4809 上使用 USART1 发送多个字符会导致发送 0xFF

Pau*_*and 4 c embedded avr avr-gcc usart

解决方案：

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事实证明它与 USART 没有任何关系。问题出在 Makefile 中。我重复使用了长期以来一直用于 atmega328p 和 atmega2560 的 Makefile。但是在将 elf 转换为 hex 文件时，此 Makefile 不包含 .rodata 部分。我想这部分从来没有用于“旧的”atmega 部件。在十六进制文件中包含 .rodata 部分后，一切都按 atmega4809 的预期工作。

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Makefile 之前的部分：

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$(OUT).hex: $(OUT).elf\n    rm -f $(OUT).hex $(OUT).eep.hex\n    $(OBJCOPY) -j .text -j .data -O ihex $(OUT).elf $(OUT).hex\n    $(SIZE) $(OUT).hex\n
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之后的 Makefile 部分：

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$(OUT).hex: $(OUT).elf\n    rm -f $(OUT).hex $(OUT).eep.hex\n    $(OBJCOPY) -j .text -j .data -j .rodata -O ihex $(OUT).elf $(OUT).hex\n    $(SIZE) $(OUT).hex\n
Run Code Online (Sandbox Code Playgroud)\n

原问题：

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以下代码的结果是：

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在此输入图像描述

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$(OUT).hex: $(OUT).elf\n    rm -f $(OUT).hex $(OUT).eep.hex\n    $(OBJCOPY) -j .text -j .data -O ihex $(OUT).elf $(OUT).hex\n    $(SIZE) $(OUT).hex\n
Run Code Online (Sandbox Code Playgroud)\n

我期待“aHello world!b”。

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写单个字符总是没问题。写入字符串时，第一个字符即可，其余字符结果为 0xFF。

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    \n

  • 我尝试过不同的波特率（结果相同）。

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    • \n

  • 不同的编译器（microchip工具链，手动构建gcc）。

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    • \n

  • 发送每个字符后添加延迟。（相同的结果）。

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    • \n
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我在这里缺少什么？

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更新：\n我更改为将代码发送至：

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$(OUT).hex: $(OUT).elf\n    rm -f $(OUT).hex $(OUT).eep.hex\n    $(OBJCOPY) -j .text -j .data -j .rodata -O ihex $(OUT).elf $(OUT).hex\n    $(SIZE) $(OUT).hex\n
Run Code Online (Sandbox Code Playgroud)\n

不幸的是没有区别：\na\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef \xbf\xbdb

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更新2，进度：

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#include <avr/io.h>\n\n#define BAUDRATE 115200\n#define BAUD_REG (F_CPU  * 64UL) / (16UL * BAUDRATE) \n\nvoid usart_init(USART_t * usart) {\n  // Sets up usart\n  usart->BAUD = BAUD_REG;\n  usart->CTRLB = (1 << USART_TXEN_bp) | (1 << USART_RXEN_bp);\n}\n\nvoid usart_write(USART_t * usart, char c) {\n    // Wait TX ready\n    while (!(usart->STATUS & USART_DREIF_bm)) {;;}\n    // Send character\n    usart->TXDATAL = c;\n}\n\nint main(void)\n{\n  // Setup 16 MHz clock internal clock\n  CCP = 0xD8;\n  CLKCTRL_MCLKCTRLB = 0;\n\n  // Setup uart1\n  // Set alternate pin mux for uart1 to PC4 and PC5\n  PORTMUX.USARTROUTEA |= PORTMUX_USART1_0_bm;\n  // Set TX pin output\n  VPORTC.DIR |= PIN4_bm;\n  // Setup USART1\n  usart_init(&USART1);\n\n  // String to send\n  char st[] = "Hello world!";\n  // Pointer to iterate of characters\n  char * st_ptr = st;\n\n  // Send char -> works fine\n  usart_write(&USART1, \'a\');\n\n  // Send string -> sends garbage\n  while (*st_ptr) {\n    usart_write(&USART1, *st_ptr++);\n  }\n\n  // Send another char -> works fine\n  usart_write(&USART1, \'b\');\n\n  while (1) {;;}\n}\n\n
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结果：\naHellob

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更新3：

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  // Send char -> works fine\n  usart_write(&USART1, \'a\');\n\n  // String to send\n  const char* st = "Hello world!";\n  uint8_t i;\n  for (i=0; i<8; i++) {\n    char s = st[i];\n    usart_write(&USART1, s);\n  }\n\n  // Send another char -> works fine\n  usart_write(&USART1, \'b\');\n
Run Code Online (Sandbox Code Playgroud)\n

不走运：\na\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\ xbf\xbdUUUUUb

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更新4（添加延迟）：

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  // Send char -> works fine\n  usart_write(&USART1, \'a\');\n\n  // String to send\n  const char* st = "Hello world!";\n  usart_write(&USART1, st[0]);\n  usart_write(&USART1, st[1]);\n  usart_write(&USART1, st[2]);\n  usart_write(&USART1, st[3]);\n  usart_write(&USART1, st[4]);\n\n  // Send another char -> works fine\n  usart_write(&USART1, \'b\');\n
Run Code Online (Sandbox Code Playgroud)\n

不走运：\na\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\ xbf\xbd你好

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更新 5：\n发现：hello world 示例\n其中使用以下代码：

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  // Send char -> works fine\n  usart_write(&USART1, \'a\');\n\n  // String to send\n  const char* st = "UUUUUUUU";\n\n  uint8_t i;\n  for (i=0; i<8; i++) {\n    char s = st[i];\n    usart_write(&USART1, s);\n  }\n\n  usart_write(&USART1, st[0]);\n  usart_write(&USART1, st[1]);\n  usart_write(&USART1, st[2]);\n  usart_write(&USART1, st[3]);\n  usart_write(&USART1, st[4]);\n\n  // Send another char -> works fine\n  usart_write(&USART1, \'b\');\n
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看起来很相似

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更新 6：\n将时钟更改为 20MHz 内部振荡器\n禁用编译器优化，makefile 片段：

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# parent directory of the toolchain, device pack, and pyupdi directories\nAVR_BASE_DIR      := /home/paul/workspace/atmega4809\n#AVR_TOOLCHAIN_DIR := $(AVR_BASE_DIR)/avr8-gnu-toolchain-$(HOST_OS)_$(HOST_ARCH)\nAVR_TOOLCHAIN_DIR := /usr\nAVR_DFP_DIR       := $(lastword $(sort $(wildcard $(AVR_BASE_DIR)/Atmel.ATmega_DFP*)))\n\n#CFLAGS_COMMON = -O2 -B $(AVR_DFP_DIR)/gcc/dev/$(DEVICE) -I $(AVR_DFP_DIR)/include -Wall -DF_CPU=$(F_CPU) -mmcu=$(DEVICE) -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -fdata-sections -ffunction-sections --param=min-pagesize=0 -mrelax -MMD -MP -Wa,-adhlns=$(OUT).lst\nCFLAGS_COMMON = -O0 -B $(AVR_DFP_DIR)/gcc/dev/$(DEVICE) -I $(AVR_DFP_DIR)/include -Wall -DF_CPU=$(F_CPU) -mmcu=$(DEVICE) --param=min-pagesize=0 -mrelax -MMD -MP -Wa,-adhlns=$(OUT).lst\n
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  // Send char -> works fine\n  usart_write(&USART1, \'a\');\n\n  // String to send\n  const char* st = "Hello world!";\n\n  uint8_t i;\n  for (i=0; i<8; i++) {\n    char s = st[i];\n    usart_write(&USART1, s);\n    _delay_ms(10);\n  }\n\n  usart_write(&USART1, st[0]);\n  usart_write(&USART1, st[1]);\n  usart_write(&USART1, st[2]);\n  usart_write(&USART1, st[3]);\n  usart_write(&USART1, st[4]);\n\n  // Send another char -> works fine\n  usart_write(&USART1, \'b\');\n
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现在字符串“st”中的每个字符都失败：\na\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef \xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbdb

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重新打开编译器优化：

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CFLAGS_COMMON = -O2 -B $(AVR_DFP_DIR)/gcc/dev/$(DEVICE) -I $(AVR_DFP_DIR)/include -Wall -DF_CPU=$(F_CPU) -mmcu=$(DEVICE) -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -fdata-sections -ffunction-sections --param=min-pagesize=0 -mrelax -MMD -MP -Wa,-adhlns=$(OUT).lst\n
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一些字符再次工作：

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a\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbdHellob

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更新7：

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void USART1_sendChar(char c)\n{\n    while (!(USART1.STATUS & USART_DREIF_bm))\n    {\n        ;\n    }        \n    USART1.TXDATAL = c;\n}\n\nvoid USART1_sendString(char *str)\n{\n    for(size_t i = 0; i < strlen(str); i++)\n    {\n        USART1_sendChar(str[i]);\n    }\n}\n
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结果为：\na\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\ xbf\xbdHe\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbdb

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# parent directory of the toolchain, device pack, and pyupdi directories\nAVR_BASE_DIR      := /home/paul/workspace/atmega4809\n#AVR_TOOLCHAIN_DIR := $(AVR_BASE_DIR)/avr8-gnu-toolchain-$(HOST_OS)_$(HOST_ARCH)\nAVR_TOOLCHAIN_DIR := /usr\nAVR_DFP_DIR       := $(lastword $(sort $(wildcard $(AVR_BASE_DIR)/Atmel.ATmega_DFP*)))\n\n#CFLAGS_COMMON = -O2 -B $(AVR_DFP_DIR)/gcc/dev/$(DEVICE) -I $(AVR_DFP_DIR)/include -Wall -DF_CPU=$(F_CPU) -mmcu=$(DEVICE) -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -fdata-sections -ffunction-sections --param=min-pagesize=0 -mrelax -MMD -MP -Wa,-adhlns=$(OUT).lst\nCFLAGS_COMMON = -O0 -B $(AVR_DFP_DIR)/gcc/dev/$(DEVICE) -I $(AVR_DFP_DIR)/include -Wall -DF_CPU=$(F_CPU) -mmcu=$(DEVICE) --param=min-pagesize=0 -mrelax -MMD -MP -Wa,-adhlns=$(OUT).lst\n
Run Code Online (Sandbox Code Playgroud)\n

结果为：\na\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\ xbf\xbd你好

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更新 8:\n切换到 usart2:\n相同的结果

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更新 9：\n它是数组的初始化：

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  // Send char -> works fine\n  usart_write(&USART1, \'a\');\n\n  // String to send\n  const char* st = "Hello world!";\n\n  uint8_t i;\n  for (i=0; i<8; i++) {\n    char s = st[i];\n    usart_write(&USART1, s);\n  }\n\n  usart_write(&USART1, st[0]);\n  usart_write(&USART1, st[1]);\n  usart_write(&USART1, st[2]);\n  usart_write(&USART1, st[3]);\n  usart_write(&USART1, st[4]);\n\n  // Send another char -> works fine\n  usart_write(&USART1, \'b\');\n
Run Code Online (Sandbox Code Playgroud)\n

结果：\naHello woHellob

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Pet*_*ník 5

这是评论中链接的反汇编blink.hex文件

Disassembly of section .sec1:

00000000 <.sec1>:
   0:   4f c0           rjmp    .+158           ;  0xa0
   2:   00 00           nop
   4:   55 c0           rjmp    .+170           ;  0xb0
   6:   00 00           nop
   8:   53 c0           rjmp    .+166           ;  0xb0
   a:   00 00           nop
   c:   51 c0           rjmp    .+162           ;  0xb0
   e:   00 00           nop
  10:   4f c0           rjmp    .+158           ;  0xb0
  12:   00 00           nop
  14:   4d c0           rjmp    .+154           ;  0xb0
  16:   00 00           nop
  18:   4b c0           rjmp    .+150           ;  0xb0
  1a:   00 00           nop
  1c:   49 c0           rjmp    .+146           ;  0xb0
  1e:   00 00           nop
  20:   47 c0           rjmp    .+142           ;  0xb0
  22:   00 00           nop
  24:   45 c0           rjmp    .+138           ;  0xb0
  26:   00 00           nop
  28:   43 c0           rjmp    .+134           ;  0xb0
  2a:   00 00           nop
  2c:   41 c0           rjmp    .+130           ;  0xb0
  2e:   00 00           nop
  30:   3f c0           rjmp    .+126           ;  0xb0
  32:   00 00           nop
  34:   3d c0           rjmp    .+122           ;  0xb0
  36:   00 00           nop
  38:   3b c0           rjmp    .+118           ;  0xb0
  3a:   00 00           nop
  3c:   39 c0           rjmp    .+114           ;  0xb0
  3e:   00 00           nop
  40:   37 c0           rjmp    .+110           ;  0xb0
  42:   00 00           nop
  44:   35 c0           rjmp    .+106           ;  0xb0
  46:   00 00           nop
  48:   33 c0           rjmp    .+102           ;  0xb0
  4a:   00 00           nop
  4c:   31 c0           rjmp    .+98            ;  0xb0
  4e:   00 00           nop
  50:   2f c0           rjmp    .+94            ;  0xb0
  52:   00 00           nop
  54:   2d c0           rjmp    .+90            ;  0xb0
  56:   00 00           nop
  58:   2b c0           rjmp    .+86            ;  0xb0
  5a:   00 00           nop
  5c:   29 c0           rjmp    .+82            ;  0xb0
  5e:   00 00           nop
  60:   27 c0           rjmp    .+78            ;  0xb0
  62:   00 00           nop
  64:   25 c0           rjmp    .+74            ;  0xb0
  66:   00 00           nop
  68:   23 c0           rjmp    .+70            ;  0xb0
  6a:   00 00           nop
  6c:   21 c0           rjmp    .+66            ;  0xb0
  6e:   00 00           nop
  70:   1f c0           rjmp    .+62            ;  0xb0
  72:   00 00           nop
  74:   1d c0           rjmp    .+58            ;  0xb0
  76:   00 00           nop
  78:   1b c0           rjmp    .+54            ;  0xb0
  7a:   00 00           nop
  7c:   19 c0           rjmp    .+50            ;  0xb0
  7e:   00 00           nop
  80:   17 c0           rjmp    .+46            ;  0xb0
  82:   00 00           nop
  84:   15 c0           rjmp    .+42            ;  0xb0
  86:   00 00           nop
  88:   13 c0           rjmp    .+38            ;  0xb0
  8a:   00 00           nop
  8c:   11 c0           rjmp    .+34            ;  0xb0
  8e:   00 00           nop
  90:   0f c0           rjmp    .+30            ;  0xb0
  92:   00 00           nop
  94:   0d c0           rjmp    .+26            ;  0xb0
  96:   00 00           nop
  98:   0b c0           rjmp    .+22            ;  0xb0
  9a:   00 00           nop
  9c:   09 c0           rjmp    .+18            ;  0xb0
  9e:   00 00           nop
  a0:   11 24           eor     r1, r1
  a2:   1f be           out     0x3f, r1        ; 63
  a4:   cf ef           ldi     r28, 0xFF       ; 255
  a6:   cd bf           out     0x3d, r28       ; 61
  a8:   df e3           ldi     r29, 0x3F       ; 63
  aa:   de bf           out     0x3e, r29       ; 62
  ac:   02 d0           rcall   .+4             ;  0xb2
  ae:   3d c0           rjmp    .+122           ;  0x12a
  b0:   a7 cf           rjmp    .-178           ;  0x0
  b2:   cd b7           in      r28, 0x3d       ; 61
  b4:   de b7           in      r29, 0x3e       ; 62
  b6:   2d 97           sbiw    r28, 0x0d       ; 13
  b8:   cd bf           out     0x3d, r28       ; 61
  ba:   de bf           out     0x3e, r29       ; 62
  bc:   88 ed           ldi     r24, 0xD8       ; 216
  be:   84 bf           out     0x34, r24       ; 52
  c0:   10 92 61 00     sts     0x0061, r1      ;  0x800061
  c4:   80 91 e2 05     lds     r24, 0x05E2     ;  0x8005e2
  c8:   84 60           ori     r24, 0x04       ; 4
  ca:   80 93 e2 05     sts     0x05E2, r24     ;  0x8005e2
  ce:   44 9a           sbi     0x08, 4 ; 8
  d0:   86 eb           ldi     r24, 0xB6       ; 182
  d2:   92 e0           ldi     r25, 0x02       ; 2
  d4:   80 93 28 08     sts     0x0828, r24     ;  0x800828
  d8:   90 93 29 08     sts     0x0829, r25     ;  0x800829
  dc:   80 ec           ldi     r24, 0xC0       ; 192
  de:   80 93 26 08     sts     0x0826, r24     ;  0x800826
  e2:   8d e0           ldi     r24, 0x0D       ; 13
  e4:   ee e2           ldi     r30, 0x2E       ; 46
  e6:   f1 e4           ldi     r31, 0x41       ; 65
  e8:   de 01           movw    r26, r28
  ea:   11 96           adiw    r26, 0x01       ; 1
  ec:   01 90           ld      r0, Z+
  ee:   0d 92           st      X+, r0
  f0:   8a 95           dec     r24
  f2:   e1 f7           brne    .-8             ;  0xec
  f4:   80 91 24 08     lds     r24, 0x0824     ;  0x800824
  f8:   85 ff           sbrs    r24, 5
  fa:   fc cf           rjmp    .-8             ;  0xf4
  fc:   81 e6           ldi     r24, 0x61       ; 97
  fe:   80 93 22 08     sts     0x0822, r24     ;  0x800822
 102:   fe 01           movw    r30, r28
 104:   32 96           adiw    r30, 0x02       ; 2
 106:   98 e4           ldi     r25, 0x48       ; 72
 108:   80 91 24 08     lds     r24, 0x0824     ;  0x800824
 10c:   85 ff           sbrs    r24, 5
 10e:   fc cf           rjmp    .-8             ;  0x108
 110:   90 93 22 08     sts     0x0822, r25     ;  0x800822
 114:   91 91           ld      r25, Z+
 116:   91 11           cpse    r25, r1
 118:   f7 cf           rjmp    .-18            ;  0x108
 11a:   80 91 24 08     lds     r24, 0x0824     ;  0x800824
 11e:   85 ff           sbrs    r24, 5
 120:   fc cf           rjmp    .-8             ;  0x11a
 122:   82 e6           ldi     r24, 0x62       ; 98
 124:   80 93 22 08     sts     0x0822, r24     ;  0x800822
 128:   ff cf           rjmp    .-2             ;  0x128
 12a:   f8 94           cli
 12c:   ff cf           rjmp    .-2             ;  0x12c
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这部分很有趣

char st[] = "Hello world!";
  e2:   8d e0           ldi     r24, 0x0D       ; R24 = 13 (string length)
  e4:   ee e2           ldi     r30, 0x2E       ; R31:R30 (Z) = 0x412E
                                                ; data address about 0x4000 is mapped progmem. 
                                                ; So Z point to address 0x012E in your code 
  e6:   f1 e4           ldi     r31, 0x41       
  e8:   de 01           movw    r26, r28        ;R29:R28 (Y) is pointer to actual stack pointer
  ea:   11 96           adiw    r26, 0x01       ;R27:R26 (X) is now pointer to st

loop:
  ec:   01 90           ld      r0, Z+
  ee:   0d 92           st      X+, r0
  f0:   8a 95           dec     r24
  f2:   e1 f7           brne    .-8             ;  0xec (loop) this loop copy 13 bytes 
                                                ;from PROMEM to SRAM to created array on the stack
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但正如您所见，十六进制文件中的地址 0x12E 没有任何内容。这里它的意思是 0xFF 值，即闪存的未编程值。

在我用 AVR studio 编译的版本中，这里是字符串的 13 个字节。并且在模拟器中一切正常。

结论您在链接或转换为十六进制文件时遇到一些问题。

编辑：我还检查blink.elf和rodata在这里

Disassembly of section .rodata:

0000412e <_end-0x7fe6d2>:
    412e:   48 65           ori r20, 0x58   ; 88
    4130:   6c 6c           ori r22, 0xCC   ; 204
    4132:   6f 20           and r6, r15
    4134:   77 6f           ori r23, 0xF7   ; 247
    4136:   72 6c           ori r23, 0xC2   ; 194
    4138:   64 21           and r22, r4
    ...
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所以这意味着问题出在转换为十六进制文件时。我的 AVR 工作室是这样做的

avr-objcopy.exe" -O ihex -R .eeprom -R .fuse -R .lock -R .signature -R .user_signatures  "GccApplication1.elf" "GccApplication1.hex"
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检查你的命令。在您的十六进制文件中，您必须找到最后 13 个字节的文本，就像我的十六进制文件一样。线路：0D01D40048656C6C6F20776F726C642100C1

:100000000C9450000C945A000C945A000C945A0012
:100010000C945A000C945A000C945A000C945A00F8
:100020000C945A000C945A000C945A000C945A00E8
:100030000C945A000C945A000C945A000C945A00D8
:100040000C945A000C945A000C945A000C945A00C8
:100050000C945A000C945A000C945A000C945A00B8
:100060000C945A000C945A000C945A000C945A00A8
:100070000C945A000C945A000C945A000C945A0098
:100080000C945A000C945A000C945A000C945A0088
:100090000C945A000C945A000C945A000C945A0078
:1000A00011241FBECFEFCDBFDFE3DEBF0E9495005E
:1000B0000C94E8000C940000CF93DF9300D0CDB7F0
:1000C000DEB789839A8389819A812BE232E0FC0131
:1000D0002087318789819A8120ECFC0126830000EA
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