at32uc3b0512-z2ues ATMEL Corporation, at32uc3b0512-z2ues Datasheet - Page 192

• Manufacturer Part Number: at32uc3b0512-z2ues
• Description: 32-bit Avr Microcontroller
• Manufacturer: ATMEL Corporation

17.7
17.7.1
17.7.2
32059J–12/2010
Programming Examples
8-bit LED-Chaser
Configuration of USART pins
It is assumed in this example that a subroutine "delay" exists that returns after a given time.
The example below shows how to configure a peripheral module to control I/O pins. It assumed
in this example that the USART receive pin (RXD) is connected to PC16 and that the USART
transmit pin (TXD) is connected to PC17. For both pins, the USART is peripheral B. In this
example, the state of the GPIO registers is assumed to be unknown. The two USART pins are
therefore first set to be controlled by the GPIO with output drivers disabled. The pins can then be
assured to be tri-stated while changing the Peripheral Mux Registers.
loop:
// Set R0 to GPIO base address
mov
orh
// Enable GPIO control of pin 0-8
mov
st.w
// Set initial value of port
mov
st.w
// Set up toggle value. Two pins are toggled
// in each round. The bit that is currently set,
// and the next bit to be set.
mov
orh
// Only change 8 LSB
mov
and
st.w
rol
rcall
rjmp
// Set up pointer to GPIO, PORTC
mov
orh
// Disable output drivers
R0, LO(AVR32_GPIO_ADDRESS)
R0, HI(AVR32_GPIO_ADDRESS)
R1, 0xFF
R0[AVR32_GPIO_GPERS], R1
R2, 0x01
R0[AVR32_GPIO_OVRS], R2
R2, 0x0303
R2, 0x0303
R3, 0x00FF
R3, R2
R0[AVR32_GPIO_OVRT], R3
R2
delay
loop
R0, LO(AVR32_GPIO_ADDRESS + PORTC_OFFSET)
R0, HI(AVR32_GPIO_ADDRESS + PORTC_OFFSET)
AT32UC3B
192