GPIO CONCEPS¶
Input configuration¶
for input mode, the output will be disabled
NOTICE * if pull up and pull down register is disabled, the input will be
noisy
Output configuration¶
for GPIO output, there’re two configuration mode * PUSH PULL * OPEN DRAIN
PUSH PULL¶
push pull uses P-MOS and N-MOS to select which circuit to output
OPEN DRAIN¶
open drain only uses N-MOS, causing output has 2 states: HIGH(zero) or FLOAT(random)
SPEEP¶
control rise time & down time
Driver API Requirement¶
- GPIO initialization
- Enable/Disable GPIO port clock
- Read From a GPIO
- Write to GPIO Pin
- Configure alternative functionality
- Interrupt handling
Initalize¶
What should initialize do for GPIO?
*
*