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UART and SPI Port Window
UART
The Use UART checkbox can be cleared if SPI is required and UART is not needed.
Crystal Frequency is a drop down box containing the frequency of the crystal currently on your
circuit. The baud rate is that of the COM port being used to communicate with the device.
Assistance with this can be found within your operating system’s documentation. The Application
Builder software calculates the required value to generate the selected Baud Rate at the chosen
crystal frequency.
The options section enables the transmitter and receiver. The 9-bit characters box adds an extra
character that can be used for parity or extra stop bit purposes.
SPI
The SPI Enable section contains an enabling checkbox. If
Data order
is checked then data is sent
MSB first, otherwise data is sent LSB first.
Clock Polarity
sets whether the SCK line is high
when idle (box is checked) or low when idle (clear).
Clock phase
selects whether the data is read on the start of a clock cycle (checked) or halfway
through a clock cycle (clear). See ATMEL Data book for more explanation.
Master/Slave Select
selects whether the SPI is to be configured as a master (checked) or slave
(clear). The
Clock Rate
drop down box becomes enabled when Master is selected and gives
prescaler options for SCK.
