AT32F421 GPIO user guide
2020.07.30
8
Rev.1.0.0
GPIO toggle
All I/O ports of AT32F421 series are fast I/Os with control registers accessible at f
AHB
speed so that
the GPIO toggle frequency can reach 60 MHz with ease.
Figure 2. I/O toggle speed
5V-tolerant or 3V-tolerant IO
Standard 3.3V-tolerant pins (TC)
All oscillators use standard 3.3V-tolerant pins.
PC14/PC15 (OSC32_IN/ OUT)
PF0/PF1 (OSC_IN/ OUT)
Table 2. TC pin example
Pin name
Pin name
IO structure
Alternate function
Additional function
PF0/OSC_IN(PF0)
I/O
TC
I2C1_SDA
OSC_IN
5V-tolerant pin with analog function (FTa)
The ports occupied by comparator input pins and ADC are 5V-tolerant pins with analog function.
PA0
– PA7
PB0
– PB2, PB12 – PB15
When configured as input floating, input pull-up or input pull-down, FTa pins are 5V tolerant;
when configured in analog mode, they are not 5V-tolerant, and input level must be less than
VDD + 0.3V at this time.
