ZBasic System Library
45
ZBasic Microcontrollers
Type
Subroutine
Invocation
ADCtoCom1(pin, rate)
Parameter
Method
Type
Description
pin
ByVal
Byte
The pin number from which analog readings will be taken.
Valid pins are those corresponding to PortA, pins 13 to 20.
rate
ByVal
int16
The rate at which conversions will be performed. The value is
the number of conversions per second and may range from 28
to 11000 samples per second.
Discussion
Calling this subroutine causes a continuous series of analog-to-digital conversions to be performed on the
signal appearing at the specified pin. Each 8-bit digital result is automatically sent out the Com1 serial
port. Before starting the conversions, the baud rate of Com1 is set to 115,200. The specified pin is
automatically set to the proper state for A/D conversion so no additional setup is required prior to use.
The conversion stream will continue until ADCToCom1() is called again with the pin parameter set to
zero (the rate parameter being meaningless in this case).
The analog input range is approximately 0.25 to 0.75 times Vcc (1.25 volts to 3.75 volts when running on
5 volts) and the resulting digital range is 0 to 255. Analog input levels below the low end of the range and
above the high end of the range will produce the low and high digital values, respectively.
Note that the subroutine Com1ToDAC() is designed to receive the data stream generated by this
Subroutine. For best accuracy, state changes on other pins of the port containing the analog input should
be avoided during the conversion process.
Resource Usage
This subroutine uses the processor’s A/D converter, Com1 and the I/O Timer. No other use of these
resources should be attempted while the conversion is active. For native code devices, the following
ISRs are required.
ISRs Required
Underlying CPU
ISR Name
mega328P, mega644P, mega128
Timer1_CompA
mega1284P
Timer3_CompA
mega1281
Timer4_CompA
mega1280
Timer4_CompA
Compatibility
This subroutine is only available on ATmega-based ZX devices.
See Also
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