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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 individualy 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.
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.
Registers
MODER, PUPDR, OTYPER, OSPEEDR
MODER
| 00 | Input (reset state) |
| 01 | Output mode |
| 10 | Alternate function mode |
| 11 | Analog input mode |
PUPDR
| 00 | No pull-up / -down (reset state) |
| 01 | Pull-up |
| 10 | Pull-down |
OSPEEDR
| 00 | Speed: 2 MHz (reset state) |
| 01 | Speed: 10 MHz |
| 10 | Speed: 50 MHz |
| 11 | Speed: 100 MHz |
OTYPER
| 0 | Output type: push-pull (reset state) |
| 1 | Output type: open-drain MHz |
AFRL/H
| 0..15 | Alternate function 0..15 |
Legend
