GPIO Port A..H
The STM32F429ZI has a total of 8 GPIO ports (A..H). Each port offers 16 I/O pins (except port H, which offers only 2). Each pin can individually be configured as input, output or be connected to one of the other peripherals (alternate function).
Features
- Up to 114 I/O ports.
- Output states: push-pull or open-drain + pull-up/-down.
- Input states: floating, pull-up/-down or analog.
- Speed selection for each I/O.
- Up to 90 MHz toggeling speed.
GPIO Register Description
Extract from ST Reference Manual
Functions
After reset most of the pins are configured as floating general purpose input. The ones that are not, are used for the debug/programming interface:
| Port A.15 | JTDI, JTAG Data Input | pull-up |
| Port A.14 | JTCK/SWCLK, JTAG / Serial Wire Clock | pull-down |
| Port A.13 | JTMS/SWDAT, JTAG Mode Select / Serial Wire Data (Input/Output) | pull-up |
| Port B.4 | NJTRST, JTAG Reset (Inverted) | pull-up |
| Port B.3 | JTDO, JTAG Data Output | floating |
These modes are available per pin:
- Input mode for reading external signals.
- Output mode for outputing signals.