Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

[SOLVED] [moved] How to control multiple Digital Pot MCP4018

Status
Not open for further replies.
kripacharya

kripacharya

Banned
Joined
Dec 28, 2012
Messages
1,204
Helped
182
Reputation
360
Reaction score
175
Trophy points
1,343
Location
New Delhi
Activity points
0
This is an I2C device, however I cannot find anything in the documentation on how to possibly control multiple such pots over the same I2C bus. Datasheet here

Except for a brief note about Phillips protocol on page 36:

Reserved 7-bit Commands (By I2C Specification - Philips # 9398 393 40011, Ver. 2.1 January 2000)
‘0000 011’b - Reset and write programmable part of slave address by hardware.
‘0000 010’b - Write programmable part of slave address by hardware.
‘0000 000’b - NOT Allowed
Click to expand...

There are no hardware address pins, and MCP4018 does not respond to General Call. There is only a single I2C slave address of 2F.

any help ?
 
Last edited by a moderator:

Re: How to control multiple Digital Pot MCP4018

I see two options:
- software I2C interface with individual SCL pins for each device
- hardware I2C interface with multiplexer for SCL, e.g. 74HC138

Because MCP4018 uses no clock-stretching, SCL is used as output only and can be switched through a digital multiplexer.
 

Re: How to control multiple Digital Pot MCP4018

Thanks FvM. These are good workarounds.

But basically you are agreeing that we cannot have multiple MCP4018 (and similar) on a 'normal' I2C bus, only one at a time. This seems a bit silly, since Microchip themselves give several examples with multiple digipots usage.

If I have to use additional lines/ pins, then I might as well use the more conventional CS/ Up/Dn interface more common on digipots.

Anyhow, thanks for the inputs.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top