attiny167-esxz ATMEL Corporation, attiny167-esxz Datasheet - Page 145

• Manufacturer Part Number: attiny167-esxz
• Description: 8-bit Avr 8-bit Microcontroller Microcontroller With 16k Bytes In-system Programmable Flash And Lin Controller
• Manufacturer: ATMEL Corporation

7728A–AUTO–07/08
The code is size optimized using only eight instructions (+ ret). The code example assumes that
the DO and USCK pins are enabled as output in the DDRA or DDRB Register. The value stored
in register r16 prior to the function is called is transferred to the Slave device, and when the
transfer is completed the data received from the Slave is stored back into the r16 Register.
The second and third instructions clears the USI Counter Overflow Flag and the USI counter
value. The fourth and fifth instruction set Three-wire mode, positive edge Shift Register clock,
count at USITC strobe, and toggle USCK. The loop is repeated 16 times.
The following code demonstrates how to use the USI module as a SPI Master with maximum
speed (fsck = fck/4):
SPITransfer_Fast:
rjmp
lds
ret
sts
ldi
ldi
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
sts
lds
ret
SPITransfer_loop
r16,USIDR
USIDR,r16
r16,(1<<USIWM0)|(0<<USICS0)|(1<<USITC)
r17,(1<<USIWM0)|(0<<USICS0)|(1<<USITC)|(1<<USICLK)
USICR,r16 ; MSB
USICR,r17
USICR,r16
USICR,r17
USICR,r16
USICR,r17
USICR,r16
USICR,r17
USICR,r16
USICR,r17
USICR,r16
USICR,r17
USICR,r16
USICR,r17
USICR,r16 ; LSB
USICR,r17
r16,USIDR
ATtiny167
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