SmallBASIC PiGPIO 2 logo
Last update: 06.02.2026

Digital Input and Output using the GPIO pins

GPIO pin numbering

The pins on the Raspberry Pi are number according to Broadcom’s GPIO numbering:

GPIO pin numbering

Library

To access the gpio pins import the library gpio:

import gpio

Function Reference

Open

Open()
Open(chipname)

Open gpio access to the chip specified by the optional parameter chipname. If chipname is not provided, the standart gpiochip of the Raspberry Pi will be opened.

SetInput

SetInput(PinNumber)
SetInput(PinNumber, Resistor)

Sets GPIO pin PinNumber as an input. If Resistor is given, the internal pullup or pulldown resistor can be set. The default setting is to use the internal pullup resistor. If Resistor is given all input pins will use this setting. (TODO: setup every pin individual.)

Before using a GPIO pin, you should use either SetInput or SetOutput.

SetOutput

SetOutput(PinNumber)

Sets GPIO pin PinNumber as an output. The initial sate of the pin is set to low. Before using a GPIO pin, you should use either SetInput or SetOutput.

SetTrigger

SetTrigger(PinNumber)
SetTrigger(PinNumber, EdgeDetection)
SetTrigger(PinNumber, EdgeDetection, Resistor)

Sets GPIO pin PinNumber as a trigger input. The optional parameter EdgeDetection defines, if the trigger is detecting rising or falling edge or both. If Resistor is given, the internal pullup or pulldown resistor can be set. The default setting is to use the internal pullup resistor. If Resistor or EdgeDetection are given all trigger input pins will use these settings. (TODO: setup every pin individual.)

Write

Write(Pin, Level)
Write(PinArray, LevelArray)
Write(PinArray, LevelBitMask)

If Pin is configured as output, the voltage level level can be set to ground (low) or +3.3V (high). Multiple pins can be set simultaneous by passing an 1D array of pin numbers. The signal levels of these pins can be set by passing an 1D array of levels. Alternative a integer number can be passed as a parameter. Every bit of this number sets a pin. The lowest bit corresponds to the first entry of the pin array.

Example:

Write(4, 0)   ' Sets pin 4 to low (ground)
Write(4, 1)   ' Sets pin 4 to high (+3.3V)
Write([4,5,6,7,8,9,10,11], [0,1,1,0,1,0,1,1])
Write([4,5,6,7,8,9,10,11], 0b11010110)

Read

Status = Read(Pin)
Status = Read(PinArray)

If Pin is configured as input, the voltage level can be read. If the specified pin is at ground (low), Status will be 1. If the pin is at +3.3V (high) Status will be 0. If an array is given, every element is a pin number. All pins will be read simultaneous. The return value Status will be an array.

Example:

Status = Read(4)   ' Reads the voltage level of pin 4
Status = Read([4,5,6,7,8,9,10,11])

Trigger

Trigger(Pin)
Trigger(Pin, Duration)
Trigger(Pin, Duration, Level)

If pin Pin is configured as output, a trigger pulse at this pin will be emitted with a Duration in microseconds and a voltage level Level of low or high.

Example:

Trigger(4, 50, 1)  ' A 50 µs Trigger pulse at pin 4 with +3.3V (high)

Wait for Trigger

Status = WaitForTrigger(Pin)
Status = WaitForTrigger(Pin, Timeout)

Wait for a raising edge event at the specified pin Pin. Timeout is in seconds. Timeout an optional parameter.

Example:

Status = WaitForTrigger(4, 1)  ' Pin 4; timeout 1s

Release Pin

ReleasePin(Pin)

Releases the pin Pin. This pin can not be used anymore until it is configured again using SetInput, SetOutput or SetTrigger.

Close

Close()

When closing a SmallBASIC program, all pins will be released. If you want to release all pins at once manually use Close.

Example Code

1. LED

In the following image you can see how to wire a LED.

LED wiring

Depending on the type of LED you need a certain resistor. When using the LED without a resistor, you will destroy the LED and maybe even parts of your Raspberry Pi.

When you buy a LED, look for two important values in the specification: Forward Voltage and Forward Current. The third important value is the Supply Voltage. In case of a Raspberry Pi it is 3.3V. Online you can find many LED resistor calculators. But if you want to see your LED blinking without studying to much and you don’t expect maximum brightness, then go for 220 Ohms or even 1000 Ohms.

Connect the resistor to pin 4 and the LED to ground.

import gpio

gpio.Open()
gpio.SetOutput(4)

for ii = 1 to 10
  v = !v
  gpio.Write(4, v)
  delay(100)
next

2. Button

In the following image you see the wiring of a push button. When you press the button, the circuit will be closed, otherwise the circuit is open. The button is connected to pin 4 and ground. An internal pullup resistor will be enabled automatically.

Wiring push button 
import gpio

v = 0

gpio.Open()
gpio.SetInput(4)

while(1)
  print gpio.Read(4)
  delay(500)
wend

3. Trigger

import gpio

v = 0

gpio.Open()
gpio.SetOutput(4)

for ii = 1 to 10
  gpio.Trigger(4)
  delay(200)
next

4. Wait for Trigger

import gpio

v = 0

gpio.Open()
gpio.SetInput(4)

result = gpio.WaitTrigger(4, 5)

select case result
  case  0: print "Time out"
  case  1: print "Rising edge detected"
  case -1: print "Error"
end select

5. Write multiple pins simultaneous

import gpio

gpio.Open()
gpio.SetOutput(18)
gpio.SetOutput(15)
gpio.SetOutput(14)
gpio.SetOutput(13)
gpio.SetOutput(12)
gpio.SetOutput(11)
gpio.SetOutput(10)
gpio.SetOutput(9)

starttime = ticks()
for ii = 1 to 100000
  v = !v
  gpio.Write([18, 15, 14, 13, 12, 11, 10, 9], [v, v, v, v, v, v, v, v])
next
print "8 pin parallel WRITE(Array, Array)    "; round(100000 / ((ticks() - starttime)/1000) /1000); "kHz"  

starttime = ticks()
v = 0b10101010
for ii = 1 to 100000
  v = v XOR 0b11111111
  gpio.Write([18, 15, 14, 13, 12, 11, 10, 9], v)
next
print "8 pin parallel WRITE(Array, Number)   "; round(100000 / ((ticks() - starttime)/1000) /1000); "kHz"

[Back to main page]