Hardware Documentation armStone
™A9
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4.11.5 ADC In
4 ADC inputs (ADC_IN0..3)
Created by an on board mounted
This feature is just available on a custom version.
4.11.6 PWM out
3 programmable PWM outputs (PWMOUT0..2) with 3.3V level in 16.1kHz up to 33 MHz
frequency range
4.11.7 Matrix keyboard
8x8 keyboard matrix (ROW0..7, COL0..1) with 3.3V level. The COL signals in pin 3..10 does
have 4.7k pull-ups on board.
4.11.8 GPIOs
GPIOs are programmable as Input or Output with 3.3V TTL level. The default maximum
driver current is 10mA (sink and source).
XGPIO0..9 do have 4.7k pull-up on module.
4.11.9 MISC signals, power
RESETBTN
3.3V TTL low active RESET input; use pushbutton to GND or open
collector driver to pull low. Don’t drive with high level.
VCC3.3, VCC5
voltage outputs for external logic, max. 100mA per pin
for external chips and functions
Backlight On
3.3V TTL high active output to switch on LCD backlight. Same signal
as on 4.6.1 and 4.7
Bootsel
only used for production. Don’t use.
