While trying to debug my UART Receive, I noticed that the TTL logic coming from hyperterminal was not making it to the RX P0_5 of the chip. I could see partial crushed signal. When I disconnect the RX line, the signal is fine, 0-3.3v TTL. It's as if the cc2540 is pulling the signal low.
I assumed that when PxSEL is set high for that pin, it automatically puts the pin into peripheral mode, setting the pin direction and pullup/pulldown status correctly.
Can anyone confirm that the pin configuration is set up properly for uart rx using DMA?
P0 = 0b11011111
P0DIR = 0b00000000
P0SEL = 0b00110000
PERCFG = 0b00000000
U1CSR = 0b11000010
U1BAUD = 0b00111011
U1UCR = 0b00000010
U1GCR = 0b00001000
IEN0 = 0b10000000
IEN1 = 0b00100101
IEN2 = 0b00000001
IRCON = 0b10000100
IRCON2 = 0b00000100
TCON = 0b00100101