 |
 |
|
 |
 |
ZBasic System Library
104
ZX Microcontroller Family
GetADC (subroutine form)
Type
Subroutine
Invocation
GetADC(pin, val)
GetADC(pin, val, fullScale)
GetADC(pin, val, fullScale, offset)
Parameter
Method
Type
Description
pin
ByVal
Byte
The pin from which to read an analog voltage.
Val
ByRef
Single
The variable in which to return the result.
fullScale
ByVal
Single
The full-scale voltage value.
offset
ByVal
Integral
The offset to apply before scaling.
Discussion
This function performs an analog-to-digital conversion on the signal present on the specified pin that must
be one of the analog port pins (see the table below). The return value will be a 10-bit (for ATxmega-
based devices) or 12-bit (for ATxmega-based devices) digital approximation of the input voltage with a
range from zero to the reference voltage (see below). For the first form, the returned value is scaled to the
range 0.0 to 1.0 and for the remaining forms it is scaled to the range 0.0 to value of the fullScale
parameter. For the third form, the value of the offset parameter (which could be negative) is added to the
10-bit ADC value before scaling. This is useful, for example, for removing the effect of a non-zero offset
voltage of the ADC.
You must make the pin an input before calling this routine.
For ATmega-based 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-based devices, the conversion is performed using a reference voltage of Vcc/1.6.
Resource Usage
Only analog port pins may be used to perform an analog-to-digital conversion. The analog port pins vary
depending on the ZX model and some ZX models have more analog input pins available. Also, on some
devices (e.g. ZX-32n, ZX-32l and ZX-328nu) some of the pins are dedicated analog inputs; having no
digital functions.
Analog Ports and Pins
ZX Models
Port
Pins
Port
Pins
ZX-24, ZX-24a, ZX-24p, ZX-24n, ZX-24r, ZX-24s
PortA
13-20
-
-
ZX-40, ZX-40a, ZX-40p, ZX-40n, ZX-40r, ZX-40s
PortA
33-40
-
-
ZX-44, ZX-44a, ZX-44p, ZX-44n, ZX-44r, ZX-44s
PortA
30-37
-
-
ZX-328n, ZX-328l
PortC
23-28
-
-
ZX-32n, ZX-32l
PortC
23-28, 19, 22
-
-
ZX-1281, ZX-1281n
PortF
54-61
-
-
ZX-1280, ZX-1280n
PortF
90-97
PortK
82-89
ZX-24x
PortA
13-20
PortB
7-9
ZX-32a4
PortA
40-44, 1-3
PortB
4-7
ZX-128a1
PortA
95-100, 1, 2
PortB
5-12
ZX-24e, ZX-24ae, ZX-24ne,
ZX-24pe, ZX-24nu, ZX-24pu, ZX-24ru, ZX-24su
PortA
29-36
-
-
ZX-24xu
PortA
29-36
PortB
25-28
ZX-128e, ZX-128ne, ZX-1281e, ZX-1281ne
PortF
29-36
-
-
ZX-328nu
PortC
17-24
-
-
|
 |
|