PICAXE Manual Section 1 - TechnoPujades - Free

www.picaxe.co.ukSection 1 57GETTING STARTEDInterfacing Circuit SummaryThis section provides a very brief overview of input/output interfacing to thePICAXE microcontroller. For more detailed explanations see section 3 of themanual - Interfacing Circuits. Section 3 provides detailed connection diagramsand sample programs for most common input / output transducers.output pin 4Digital OutputsThe microcontroller can sink orsource 20ma on each output pin,maximum 90mA per chip. Thereforelow current devices such as LEDs canbe interfaced directly to the outputpin. Higher current devices can beinterfaced via a transistor, FET ordarlington driver array.5V0V330RMPICAXE0VDigital InputsDigital input switches can beinterfaced with a 10k pull downresistor. The resistor is essential as itprevents the input ‘floating’ when theswitch is in th open position. Thiswould give unreliable operation.5Vinput pinNote the 10k resistor is pre-fitted tothe project board inputs.10kPICAXE0VV+Analogue InputsAnalogue inputs can be connected in apotential divider arrangement between V+and 0V. The analogue reference is thesupply voltage, and the analogue signalmust not exceed the supply voltage.analogueinputADC pinPICAXE0Vrevolution(c) Revolution Education Ltd. Email: info@rev-ed.co.uk Web: www.rev-ed.co.ukVersion 6.9 07/2009All rights reserved.57