Ich habe 2 Boards (Controller = ATMEL AT90PWM316) miteinander über die
ISP-Schnittstelle verbunden und möchte vom Master Daten an den Slave
senden und diese dort am PORTC ausgeben.
CLK, SS und MOSI habe ich mit dem Oszi am Master gemessen. Hier ist
alles OK!
Mein Problem ist, dass ich die Übertragung am PORTC nur empfange, wenn
ich das Programm Schritt für Schritt im Debugger durchsteppe.
Hier mein C-Code für den Master:
1 | #include <avr/io.h>
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2 | #include <util/delay.h>
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3 |
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4 | void SPI_Master_Init(void)
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5 | {
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6 | SPCR &= ~(1<<DORD); // Send MSB first
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7 | SPCR |= (1<<MSTR); // Controller = Master
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8 | SPCR &= ~(1<<CPOL); // CLK positiv phase
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9 | SPCR |= (1<<CPHA); // Sampling data @ rising edge
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10 | SPCR |= (1<<SPR1); // CLK / 64 = 125kHz
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11 |
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12 | DDRB |= (1<<PB1); // Set MOSI output
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13 | DDRB |= (1<<PB7); // Set SCK output
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14 |
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15 | DDRD |= (1<<PD3); // Set SS output
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16 |
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17 | SPCR |= (1<<SPE); // SPI enable
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18 | }
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19 |
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20 | void SPI_Master_Transmit(char cData)
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21 | {
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22 | PORTD &= ~(1<<PD3); // SS = low
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23 | SPDR = cData; // Start transmission
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24 | while (!(SPSR & (1<<SPIF))); // Wait for transmission complete
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25 | PORTD |= (1<<PD3); // SS = high
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26 | }
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27 |
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28 | void main(void)
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29 | {
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30 | SPI_Master_Init();
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31 |
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32 | while(1)
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33 | {
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34 | SPI_Master_Transmit(0b11010010);
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35 | _delay_ms(500); // delaytime between next transmission
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36 | SPI_Master_Transmit(0b00000001);
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37 | _delay_ms(500);
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38 | }
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39 | }
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Hier mein C-Code für den Slave:
1 | #include <avr/io.h>
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2 | #include <util/delay.h>
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3 |
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4 |
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5 |
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6 | void SPI_Slave_Init(void)
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7 | {
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8 | SPCR &= ~(1<<DORD); // Send MSB first
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9 | SPCR &= ~(1<<MSTR); // Controller = Slave
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10 | SPCR &= ~(1<<CPOL); // CLK positiv phase
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11 | SPCR |= (1<<CPHA); // Sampling data @ rising edge
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12 | SPCR |= (1<<SPR1); // CLK / 64 = 125kHz
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13 |
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14 | DDRB |= (1<<PB0); // Set MISO output
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15 | DDRB &= ~(1<<PB1); // Set MOSI input
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16 | DDRB &= ~(1<<PB7); // Set SCK input
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17 |
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18 | SPCR |= (1<<SPE); // SPI enable
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19 | }
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20 |
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21 | unsigned char SPI_Slave_Receive()
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22 | {
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23 | while (!(SPSR & (1<<SPIF))); // Wait for transmission complete
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24 | return SPDR;
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25 | }
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26 |
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27 | void main(void)
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28 | {
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29 | DDRC = 0xFF;
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30 |
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31 | SPI_Slave_Init();
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32 |
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33 | while(1)
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34 | {
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35 | SPI_Slave_Receive();
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36 | PORTC = SPI_Slave_Receive();
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37 | _delay_us(50); // delaytime between next transmission
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38 | }
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39 | }
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