Rainbow-electronics ATtiny26L Manuel d'utilisateur télécharger pdf (Page 70)

ATtiny26(L)

1477B–AVR–04/02

The following code demonstrates how to use the USI module as a SPI Master with max-

imum speed (fsck = fck/2):

SPITransfer_Fast:

out USIDR,r16

ldi r16,(1<<USIWM0)+(0<<USICS0)+(1<<USITC)

ldi r17,(1<<USIWM0)+(0<<USICS0)+(1<<USITC)+(1<<USICLK)

out USICR,r16 ; MSB

out USICR,r17

out USICR,r16

out USICR,r17

out USICR,r16

out USICR,r17

out USICR,r16

out USICR,r17

out USICR,r16

out USICR,r17

out USICR,r16

out USICR,r17

out USICR,r16

out USICR,r17

out USICR,r16 ; LSB

out USICR,r17

in r16,USIDR

ret

SPI Slave Operation Example The following code demonstrates how to use the USI module as a SPI slave:

init:

ldi r16,(1<<USIWM0)+(1<<USICS1)

out USICR,r16

...

SlaveSPITransfer:

out USIDR,r16

ldi r16,(1<<USIOIF)

out USISR,r16

SlaveSPITransfer_loop:

sbis USISR,USIOIF

rjmp SlaveSPITransfer_loop

in r16,USIDR

ret

The code is size optimized using only 8 instructions (+ ret). The code example assumes

that the DO is configured as output and SCK pin is configured as input in the DDRB

the master device, and when the transfer is completed the data received from the mas-

ter is stored back into the r16 register.

1 2 ... 65 66 67 68 69 70 71 72 73 74 75 ... 150 151

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Rainbow-electronics ATtiny26L Manuel d'utilisateur Page 70

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