Functions for setting voltages with D/A0, D/A1 outputs and measuring voltages with A/D0...A/D3 inputs. More...

#include "simpletools.h"

Macros
#define	_abvolts_EE_start_ 63400
	abvolts EEPROM calibration data start address.
#define	_abvolts_EE_end_ 63400 + 16
	abvolts EEPROM calibration data end address.

Functions
void	da_init (int pinDA0, int pinDA1)
	Set output pins for D/A0 and D/A1.
void	ad_init (int csPin, int sclPin, int doPin, int diPin)
	Initialize Activity Board A/D converter.
void	da_volts (int channel, float daVal)
	Set D/A voltage (0 to ~3.3 V) on a given channel (0 or 1 for D/A0 or D/A1). Actual voltage will be the closest match of 256ths of 3.3 V.
float	ad_volts (int channel)
	Get a voltmeter style floating point voltage measurement from one of the A/D converter's input channels.
void	da_out (int channel, int daVal)
	Set D/A output.
int	ad_in (int channel)
	Get input value that corresponds to voltage measurement on one of the A/D converter's input channels. This number indicates voltage in terms of 4096ths of 5 V.
void	da_res (int bits)
	Set D/A voltage resolution.
void	da_setupScale (void)
	Set up scale to adjust D/A0 and D/A1. Connect DA/0 to AD/0 and DA/1 to AD/1 before running. Writes scalars to EEPROM memory. These scalars can be retrieved with da_getScale();.
void	da_useScale (void)
	Load scale that adjusts D/A0 and D/A1. If you have not called da_setScale some time in the past, this will not have any affect.
void	da_stop (void)
	Stop the cog that's transmitting the D/A signal(s).

Detailed Description

Functions for setting voltages with D/A0, D/A1 outputs and measuring voltages with A/D0...A/D3 inputs.

Author: Andy Lindsay

Copyright: Copyright (C) Parallax, Inc. 2013. All Rights MIT Licensed.

Core Usage: A call to either da_volts or da_out will launch 1 additional core. Both functions rely on code running in that additional core. More calls to either function will not result in more cores being launched.

EEPROM Usage: da_setupScale writes to addresses 63400..63416.

Memory Models: Use with CMM or LMM.

Version: 0.5

Help Improve this Library: Please submit bug reports, suggestions, and improvements to this code to edito.nosp@m.r@pa.nosp@m.ralla.nosp@m.x.co.nosp@m.m.

Function Documentation

int ad_in ( int channel )

Get input value that corresponds to voltage measurement on one of the A/D converter's input channels. This number indicates voltage in terms of 4096ths of 5 V.

Parameters

channel The A/D converter's input channel, either channel 0, 1, 2, or 3. Marked A/D 0, 1, 2 or 3 on the Propeller Activity Board.

Returns: Voltage measurement as a number of 4096ths of 5 V.

void ad_init	(	int	csPin,
		int	sclPin,
		int	doPin,
		int	diPin
	)

Initialize Activity Board A/D converter.

Call this function once before calling ad_in or ad_volts.

Propeller Activity Board Example:

adc_init(21, 20, 19, 18);

Parameters

csPin	Propeller I/O pin connected to the A/D converter's chip select pin. The Propeller chip uses that pin to enable communication with the A/D converter chip. This connection is labeled /CS-P21 on the Propeller Activity Board. In that case Propeller I/O pin P21 is connected to the A/D converter's chip select pin, so you would use 21 for this parameter.
sclPin	Propeller I/O pin connected to the A/D converter's serial clock pin. The Propeller chip sends a series of pulses to the A/D converter's SCL pin to drive the conversion and signal to send/receive binary conversion values. This connection is labeled SCL-P20 on the Propeller Activity Board. In that case Propeller I/O pin P20 is connected to the A/D converter's serial clock pin, so you would use 20 for this parameter.
doPin	Propeller I/O pin connected to the A/D converter's data out pin. The A/D converter sends binary values to the controller with this pin. This connection is labeled DO-P19 on the Propeller Activity Board. In that case Propeller I/O pin P19 is connected to the A/D converter's data out pin, so you would use 19 for this parameter.
diPin	Propeller I/O pin connected to the A/D converter's data in pin. The Propeller chip sends a channel selection to the A/D converter, which receives it with this pin. This connection is labeled DI-P18 on the Propeller Activity Board. In that case Propeller I/O pin P18 is connected to the A/D converter's chip data in, so you would use 18 for this parameter.

float ad_volts ( int channel )

Get a voltmeter style floating point voltage measurement from one of the A/D converter's input channels.

Parameters

channel The A/D converter's input channel, either channel 0, 1, 2, or 3. Marked A/D 0, 1, 2 or 3 on the Propeller Activity Board.

Returns: Floating point value that represents the voltage measurement.

void da_init	(	int	pinDA0,
		int	pinDA1
	)

Set output pins for D/A0 and D/A1.

If this function is not called, the default is D/A0 = 26 and D/A1 = 27, which go the D/A0 and D/A1 sockets on the Activity Board. These sockets can supply current loads while maintaining the output voltage. Other I/O pins can be used, for LED brightness and other circuits that do not draw current loads.

Parameters

pinDA0	D/A0 pin.
pinDA1	D/A1 pin.

void da_out	(	int	channel,
		int	daVal
	)

Set D/A output.

Launches process into another cog for up to two channels of D/A conversion on any I/O pin. Other libraries may be available that provide D/A for more channels. Check SimpleIDE/Learn/Simple Libraries/Convert for options. For more options, check obex.parallax.com.

This library uses another cog's counter modules (2 per cog) to perform duty modulation, which is useful for D/A conversion. The digital signal it generates will affect LED brightness. The signal can be passed through a low pass RC filter for digital to analog voltage conversion. Add an op amp buffer if it needs to drive a load. The D/A0 and D/A1 circuits use this type of circuit.

Default resolution is 8 bits for output voltages ranging from 0 V to (255/256) of 3.3 V.

General equation is daVal * (3.3 V/2^bits)

Default is 8 bits, which results in daVal * (3.3 V/ 256), so daVal specifies the number of 256ths of 3.3 V. You can change the resolution with the da_res function.

Parameters

channel	Use 0 or 1 to select the cog's CTRA or CTRB counter modules, which are used for D/A conversion.
daVal	Number of 256ths of 3.3 V by default. Use a value from 0 (0 V) to 255 .

void da_res ( int bits )

Set D/A voltage resolution.

Default resolution is 8-bits for output voltages ranging from 0 V to (255/256) of 3.3 V.

General equation is daVal * (3.3 V/2^bits)

Default is 8 bits, which results in daVal * (3.3 V/ 256), so daVal specifies the number of 256ths of 3.3 V.

Parameters

bits	The D/A converter's resolution in bits.

void da_setupScale ( void )

Set up scale to adjust D/A0 and D/A1. Connect DA/0 to AD/0 and DA/1 to AD/1 before running. Writes scalars to EEPROM memory. These scalars can be retrieved with da_getScale();.

Measures high signal to D/A0 and D/A1 and use any difference in 3.3 V signal to set output scalars that are stored in EEPROM.

void da_stop ( void )

Stop the cog that's transmitting the D/A signal(s).

Stops any signals, lets go of any I/O pins, and reclaims the cog for other uses.

void da_useScale ( void )

Load scale that adjusts D/A0 and D/A1. If you have not called da_setScale some time in the past, this will not have any affect.

Retrievels scalars for adjusting D/A outputs from EEPROM and uses them for subsiquent D/A conversions.

void da_volts	(	int	channel,
		float	daVal
	)

Set D/A voltage (0 to ~3.3 V) on a given channel (0 or 1 for D/A0 or D/A1). Actual voltage will be the closest match of 256ths of 3.3 V.

Parameters

channel	Use for D/A0 or 1 for D/A1. .*
daVal	floating point number of volts.

Macros

Functions

Detailed Description

Function Documentation