DS3502

Digital Potentiometer (POT)

• Operation
• Api
• Tools

:gear: Operation

The Digital Potentiometer uses a resistory array to achive a 0-127 step range between its high (RH) and low value (RL). In most cases these are wired to the same logic high and low. Thus, providing a POT output (on RW) for analog usage in the RH-RL range.

In addition to the controllable wiper value (via WR) the device provides the ability to set the initialization value on startup. This is provided via a mode change such that writes to the wiper value are preserved in a persistant storage on the chip (withing IVR on the EEPROM).

This set-and-update mode while usefull for setting persistent values over power loss also comes with increassed delay in update.

:warning: mode changes to the control register (CR) do not take effect until the next write phase

:warning: it is not recommended to update both CR and WR in a single update, although it is supported

:book: API

The primary interface is the exposed DS3502 class. Which expose a factory method from and primary class methods of setProfile and profile.

And example of typical usage:

import { I2CAddressedBus } from '@johntalton/and-other-delights'
import { DS3502 } from '@johntalton/ds3502'

const busNumber = 1
const busAddress = 0x28

const ds = await DS3502.from(new I2CAddressedBus(i2c1, bus))

const profile = await ds.profile() // { WR: 127, CR: 0 }

profile

Returns asynchronously and object with properties for the wiper (WR) and control (CR). The initialization value of the wiper (IVR) can not be inspected.

setProfile

Sets asynchronously the devices profile via and object with properties for wiper (WR) and control (CR). Both wiper WR and CR mode update can be specified in a single update. However, the POTs value update to the wiper (WR) will respect the previous mode value.

:wrench: Tools

get

Fetches and returns the current devices profile.

set

Sets one or more values of the devices.

And example of using the set command to blink and LED twice with a half second delay in update-only mode:

>node set.mjs mode 128 pot 0 delay 500 pot 127 pot 100 pot 127 pot 0