AVR Freaks

Here is similar code update from what mraardvark posted in another thread.

The "putchar" demo, between "#if 0" and "#else" works fine: it prints out "hi" in my minicom session.

The,the "putline" fails: it prints out continuous garbage.  If I limit the loop in putline to two characters it prints two garbage characters.

This is what I traced down to what I thought was unintialized data.  Now that I look again with "objdump -D" instead of "objdump -d" I see there is a .rodata section with hex 68, 'h', and 69, 'i', at 0x415c, and the call to putline with the correct address 0x415c as argument.  

So I have again I am left clueless.

#define F_CPU 20000000
#include <avr/io.h>
#include <util/delay.h>

#define BAUDRATE 9600
#define BAUD_FROM_RATE(RATE) ((4UL * (F_CPU))/(RATE))

void uart_init(void)
{
  USART3.BAUD = BAUD_FROM_RATE(BAUDRATE);
  USART3.CTRLC = USART_SBMODE_2BIT_gc | USART_CHSIZE_8BIT_gc;
}

void uart_on(void)
{
  // Enable TX
  USART3.CTRLB = USART_TXEN_bm;
  // TX pin to output
  PORTB.DIRSET = (1 << 0);
}

void uart_off(void)
{
  // Disable TX
  USART3.CTRLB &= ~USART_TXEN_bm;
}

void uart_putchar(char c)
{
  // Wait for space
  while (!(USART3.STATUS & USART_DREIF_bm)) ;
  USART3.TXDATAL = c;
}

void uart_putline(char *p)
{
   while (*p != '\0') {
      uart_putchar(*p++);
   }
   uart_putchar('\r');
   uart_putchar('\n');
}

int main(void)
{
  // TX pin pullup enable
  PORTB.PIN0CTRL = PORT_PULLUPEN_bm;

  // Button pullup
  PORTF.PIN6CTRL = PORT_PULLUPEN_bm;

  // Setup 20MHz clock
  _PROTECTED_WRITE((CLKCTRL.MCLKCTRLB), (0 << CLKCTRL_PEN_bp));

  // UART init
  uart_init();

  while (1) {
    // Wait for button
    while (PORTF.IN & (1 << 6)) ;

    uart_on();
#if 0
    uart_putchar('h');
    uart_putchar('i');
    uart_putchar('\r');
    uart_putchar('\n');
#else
    uart_putline("hi");
#endif
    uart_off();
    _delay_ms(100);
  }
}

Here is disassembled code via "objdump -D" with debug sections removed and interrupt list trimmed:

Disassembly of section .text:

00000000 <__vectors>:
   0:	0c 94 50 00 	jmp	0xa0	; 0xa0 <__ctors_end>
   4:	0c 94 5a 00 	jmp	0xb4	; 0xb4 <__bad_interrupt>
...
  98:	0c 94 5a 00 	jmp	0xb4	; 0xb4 <__bad_interrupt>
  9c:	0c 94 5a 00 	jmp	0xb4	; 0xb4 <__bad_interrupt>

000000a0 <__ctors_end>:
  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:	0e 94 8a 00 	call	0x114	; 0x114 <main>
  b0:	0c 94 ac 00 	jmp	0x158	; 0x158 <_exit>

000000b4 <__bad_interrupt>:
  b4:	0c 94 00 00 	jmp	0	; 0x0 <__vectors>

000000b8 <uart_init>:
  b8:	e0 e6       	ldi	r30, 0x60	; 96
  ba:	f8 e0       	ldi	r31, 0x08	; 8
  bc:	8d e8       	ldi	r24, 0x8D	; 141
  be:	90 e2       	ldi	r25, 0x20	; 32
  c0:	80 87       	std	Z+8, r24	; 0x08
  c2:	91 87       	std	Z+9, r25	; 0x09
  c4:	8b e0       	ldi	r24, 0x0B	; 11
  c6:	87 83       	std	Z+7, r24	; 0x07
  c8:	08 95       	ret

000000ca <uart_on>:
  ca:	80 e4       	ldi	r24, 0x40	; 64
  cc:	80 93 66 08 	sts	0x0866, r24	; 0x800866 <__TEXT_REGION_LENGTH__+0x7f4866>
  d0:	81 e0       	ldi	r24, 0x01	; 1
  d2:	80 93 21 04 	sts	0x0421, r24	; 0x800421 <__TEXT_REGION_LENGTH__+0x7f4421>
  d6:	08 95       	ret

000000d8 <uart_off>:
  d8:	e0 e6       	ldi	r30, 0x60	; 96
  da:	f8 e0       	ldi	r31, 0x08	; 8
  dc:	86 81       	ldd	r24, Z+6	; 0x06
  de:	8f 7b       	andi	r24, 0xBF	; 191
  e0:	86 83       	std	Z+6, r24	; 0x06
  e2:	08 95       	ret

000000e4 <uart_putchar>:
  e4:	90 91 64 08 	lds	r25, 0x0864	; 0x800864 <__TEXT_REGION_LENGTH__+0x7f4864>
  e8:	95 ff       	sbrs	r25, 5
  ea:	fc cf       	rjmp	.-8      	; 0xe4 <uart_putchar>
  ec:	80 93 62 08 	sts	0x0862, r24	; 0x800862 <__TEXT_REGION_LENGTH__+0x7f4862>
  f0:	08 95       	ret

000000f2 <uart_putline>:
  f2:	cf 93       	push	r28
  f4:	df 93       	push	r29
  f6:	ec 01       	movw	r28, r24
  f8:	89 91       	ld	r24, Y+
  fa:	81 11       	cpse	r24, r1
  fc:	08 c0       	rjmp	.+16     	; 0x10e <__EEPROM_REGION_LENGTH__+0xe>
  fe:	8d e0       	ldi	r24, 0x0D	; 13
 100:	0e 94 72 00 	call	0xe4	; 0xe4 <uart_putchar>
 104:	8a e0       	ldi	r24, 0x0A	; 10
 106:	df 91       	pop	r29
 108:	cf 91       	pop	r28
 10a:	0c 94 72 00 	jmp	0xe4	; 0xe4 <uart_putchar>
 10e:	0e 94 72 00 	call	0xe4	; 0xe4 <uart_putchar>
 112:	f2 cf       	rjmp	.-28     	; 0xf8 <uart_putline+0x6>

00000114 <main>:
 114:	88 e0       	ldi	r24, 0x08	; 8
 116:	80 93 30 04 	sts	0x0430, r24	; 0x800430 <__TEXT_REGION_LENGTH__+0x7f4430>
 11a:	80 93 b6 04 	sts	0x04B6, r24	; 0x8004b6 <__TEXT_REGION_LENGTH__+0x7f44b6>
 11e:	88 ed       	ldi	r24, 0xD8	; 216
 120:	90 e0       	ldi	r25, 0x00	; 0
 122:	84 bf       	out	0x34, r24	; 52
 124:	90 93 61 00 	sts	0x0061, r25	; 0x800061 <__TEXT_REGION_LENGTH__+0x7f4061>
 128:	0e 94 5c 00 	call	0xb8	; 0xb8 <uart_init>
 12c:	80 91 a8 04 	lds	r24, 0x04A8	; 0x8004a8 <__TEXT_REGION_LENGTH__+0x7f44a8>
 130:	86 fd       	sbrc	r24, 6
 132:	fc cf       	rjmp	.-8      	; 0x12c <main+0x18>
 134:	0e 94 65 00 	call	0xca	; 0xca <uart_on>
 138:	8c e5       	ldi	r24, 0x5C	; 92
 13a:	91 e4       	ldi	r25, 0x41	; 65
 13c:	0e 94 79 00 	call	0xf2	; 0xf2 <uart_putline>
 140:	0e 94 6c 00 	call	0xd8	; 0xd8 <uart_off>
 144:	2f e7       	ldi	r18, 0x7F	; 127
 146:	8a e1       	ldi	r24, 0x1A	; 26
 148:	96 e0       	ldi	r25, 0x06	; 6
 14a:	21 50       	subi	r18, 0x01	; 1
 14c:	80 40       	sbci	r24, 0x00	; 0
 14e:	90 40       	sbci	r25, 0x00	; 0
 150:	e1 f7       	brne	.-8      	; 0x14a <main+0x36>
 152:	00 c0       	rjmp	.+0      	; 0x154 <main+0x40>
 154:	00 00       	nop
 156:	ea cf       	rjmp	.-44     	; 0x12c <main+0x18>

00000158 <_exit>:
 158:	f8 94       	cli

0000015a <__stop_program>:
 15a:	ff cf       	rjmp	.-2      	; 0x15a <__stop_program>

Disassembly of section .rodata:

0000415c <_end-0x7fe6a4>:
    415c:	68 69       	ori	r22, 0x98	; 152
	...

I added DIRSET before the OUTSET for tx pin.  Also sprinkled in _delay_ms(1) after putchar in the loop and in putchar between reading uart status and writing to TXDATA.  No luck.

I tried _delay_ms(2) and _delay_ms(4) -- didn't work.

PB0 according to the curiosity nano datasheet (= CDC RX).