PICAXE Manual Section 1 - TechnoPujades - Free

www.picaxe.co.ukSection 1 39GETTING STARTEDReset CircuitAll 18, 28 and 40 pin PICAXE have a ‘reset’ pin. This pin must be in the highcondition for the PICAXE microcontroller to function. If this pin is leftunconnected the microcontroller will not operate reliably. To tie this pin highconnect a 4.7k resistor between the reset pin and V+ supply rail (do not connectthe pin directly to V+, always use a resistor). A reset switch is optional, but highlyrecommended. This should be a ‘push to make’ type and connected between thereset pin and 0V.All 8, 14 and 20 pin PICAXE do not have a reset pin. Therefore to reset themicrocontroller the power supply must be disconnected and then reconnected.Note that, when using capacitors in your supply circuit, these capacitors may holdenough charge to keep the microcontroller powered for several seconds after thepower supply is disconnected.ResonatorDifferent PICAXE chips have internal or external (or both) options:PICAXE INTERNAL EXTERNAL08 4 -08M 4,8 -14M 4,8 -18 4 -18A 4,8 -18M 4,8 -18X 4,8 -20M 4,8 -20X2 4,8,16,32,64 -28A - 428X - 4,8,1628X1 4,8 4,8,1628X2 4,8 4 (=16), 8 (=32), 10 (=40)28X2-3V 4,8,16 4 (=16), 8 (=32), 10 (=40), 16 (=64)40X - 4,8,1640X1 4,8 4,8,1640X2 4,8 4 (=16), 8 (=32), 10 (=40)40X2-3V 4,8,16 4 (=16), 8 (=32), 10 (=40), 16 (=64)All 28 and 40 pin PICAXE can use an external resonator (the resonator is internalwithin the 08, 14, 20 and 18 pin PICAXE). Note that the internal resonatorwithin the 08,14,20 and 18 PICAXE is not quite as accurate as an externalresonator. Although this does not cause any issues with the majority of projects, ifa specialised project requires very high precision a 28 or 40pin PICAXE should beused.An 3 pin ceramic resonator is recommended when required. This device consistsof a resonator and two loading capacitors in a single 3 pin package. The centrepin is connected to 0V and the outer two pins to the two PICAXE resonator pins(the resonator can be used either way around).revolution(c) Revolution Education Ltd. Email: info@rev-ed.co.uk Web: www.rev-ed.co.ukVersion 6.9 07/2009All rights reserved.39