Debounce circuits are included where electromechanical switches are expected, although external pull-up resistors must be added.
“The LSI/CSI digital potentiometers are used as replacements for mechanical potentiometers and for potentiometer adjustments,” according to distributor Omni Pro, which will be stocking the parts. “They can also be used for remote adjustments of instrumentation for gain, offset, time constant, line impedance matching or audio equipment volume control.”
The parts are:
- LS7190 debounced incremental encoder quadrature, and SPI
- LS7191 debounced up and down push buttons, and SPI
- LS7192 up clock and down clock from GPIO, and SPI
- LS7193 debounced incremental encoder quadrature
- LS7194 debounced up and down push buttons
- LS7195 up clock and down clock from GPIO
All are available in 20, 50 or 100kΩ versions – the data sheet does not appear to give a tolerance on this.
At power-up, the wiper is set to ’32’ (mid-point), and SPI versions get a pin to reset the wiper to this position at any time as well as the serial bus to set in to any position without stepping through intermediate values.
A setting of ‘0’ takes the wiper all the way to the ‘T b’ end of the potentiometer (see diagram), while ’63’ takes it one resistor short of the ‘Ta’ end of the potentiometer.
The serial bus also allows a host microcontroller to read the wiper position, allowing it to know where the electromechanical controls have set it, for instance to save a setting at power-down.
Quadrature parts count only on the rising edge of the A input – so pick your encoder with this in mind.
Counting in LS7193 and LS7194 is enabled all the time, while the other devices have an (internally pulled-up) enable pin to allow adjustment to be inhibited. Where debounce is provided, its timing is set by a single external capacitor.
Power can be anywhere from 3.0 to 5.0V (7V abs max), and the three potentiometer connections can be made at potentials anywhere within the power rails. Operation is over -40°C to +125°C.
Parts with an SPI bus come in a choice of SOIC-14 or TSSOP-14, and those without a serial bus only come in SOIC-8.
Omni Pro’s LS719x product page is here
The data sheet can be found on LSI/CSI’s website here – and it includes sample Arduino code for evaluation.
"interface" - Google News
April 12, 2022 at 05:15PM
https://ift.tt/mwhEBQT
Digital pots interface directly with quadrature encoders, push buttons and MCUs - Electronics Weekly
"interface" - Google News
https://ift.tt/pBjuDeg
https://ift.tt/yi3xoBE
Bagikan Berita Ini
0 Response to "Digital pots interface directly with quadrature encoders, push buttons and MCUs - Electronics Weekly"
Post a Comment