Using 7 3-wire RTDs with the same chip?

Rotem Segev

Other Parts Discussed in Thread: ADS1248, LMP90100, ADS1118

Hello

My application requires measuring 7 RTDs (all of them are 3 wire configuration). They need to interface to the ARM 32F103 microcontroller via SPI.

The problem is I only have 1 SPI port available for communication, and the LMP90100/ ADS1248 have only 4 inputs for 3 wire RTD, so I need to use 2 each.

How can I implement this?

over 12 years ago

0 Bob Benjamin over 12 years ago

TI__Guru** 113765 points

Hi Rotem,

Welcome to the forum! This is usually accomplished by using GPIO from the controller to drive the CS (chip select) pin for the SPI. In this way you can choose which device you are communicating and getting data.

Best regards,

Bob B

0 Rotem Segev over 12 years ago in reply to Bob Benjamin

Prodigy 80 points

Thanks for your answer. So is it possible to connect two ADS1248 to one SPI channel?

Is there an app note describing that?

I just want to be sure.

0 Bob Benjamin over 12 years ago in reply to Rotem Segev

TI__Guru** 113765 points

Rotem,

I don't have anything that is specific to the ADS1248, but on page 26 of the ADS1118 datasheet you can find the following diagram and a discussion on using multiple devices.

Best regards,

Bob B

Data converters

Data converters forum

Using 7 3-wire RTDs with the same chip?