ZBasicSysLib - page 141 of 346

Page 141 of 346

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ZBasic System Library

ZBasic Microcontrollers

GetADC (function form)

Function returning Integer

The pin from which to read an analog voltage.

This function performs an analog-to-digital conversion of the voltage present on the specified pin which

must be one of the analog port pins (see the table below). The return value will be a 10-bit digital

approximation of the input voltage with a range from zero to the reference voltage (see below). The

return value represents the measured voltage voltage according to the formula V

is the reference voltage, adcVal is the value returned by GetADC(), and FS is 1024 for mega-

based devices and 4096 for xmega-based devices.

You must make the specified pin an input before calling this routine.

For ATtiny and ATmega target devices, the conversion is performed using the AVcc reference voltage

(connected internally to Vcc on the ZX-24, ZX-24a, ZX-24p, ZX-24n, ZX-24r, ZX-24s, ZX-24e, ZX-24ae,

ZX-24ne, ZX-24pe, ZX-24nu, ZX-24pu, ZX-24ru, ZX-24su, ZX-328nu, ZX-128e, ZX-128ne, ZX-1281e and

ZX-1281ne). For ATxmega target devices, the conversion is performed using a reference voltage of

Only analog port pins may be used to perform an analog-to-digital conversion. The number and location

of analog port pins vary depending on the ZBasic target device. See the section Analog-to-Digital

Converters for more information.

Most ZBasic target devices contain a single analog-to-digital converter thus allowing only one conversion

to be performed at a time (some have none at all). The conversion process takes approximately 220uS

during which time the calling task will be awaiting conversion completion.

Although the BasicX manual indicates that that it is not necessary to configure the pin to be an input

before calling, tests indicate that it is, in fact, necessary to do so. Consequently, the behavior of this

implementation matches the actual behavior of the BasicX platform.