Other Parts Discussed in Thread: TMS320F28335, CONTROLSUITE
On my TMS320F28335 processor:
When I configured the GPIO16, 17, 18 and 19 pins as GPIO purpose, they could drive my peripherial device (an SPI serial device) at a correct logic level. The peripherial device is connected to these pins directly without any external pull-up or pull-down resistors.
However, when I confiugred them (GPIO16, 17, 18 and 19 pins) as SPI port ( in this case, the GPIO16 pin acts as SPISIMOA ), I found that the GPIO16 pin was unable to drive my peripheral device at a correct logic high level. It only gives 1.3V at the pin for a logic high. A logic low is correct at this pin. The other pins for the SPI ports seemed ok.
Questions:
1. What might cause this problem? If the SPI is not initilized correctly, would it cause this problem - inadequate logic high level at the SPI output pin?
2. The drive capability of these pins (GPIO16, 17, 18 and 19 pins) seemed to be different when you configure them as GPIO or SPI. Correct? If so, what is the SPI drive capability? A GPIO pin could drive 4mA maximum. Is it the same when the pin is configured as an SPI output pin?
3. When I configure them as SPI port, do I need the external pull-up resistors, or a buffer to drive my SPI peripheral device which has 600uA pull-down?
Thank you very much in advance!
