TIDM-MSP430AFE253SUBMETEREVM: Serial Communication Circuit

Paul Canon

Part Number: TIDM-MSP430AFE253SUBMETEREVM

Can someone help me understand this circuit?
it is part of a evaluation board and this circuit is used is for serial communication, i'm having trouble understanding how this circuit works?
and also can i directly connect RXD,TXD and DGND pins to a microcontroller for communication instead of having DB( connector?

over 5 years ago

0 Keith Barkley over 5 years ago

Guru 42085 points

This circuit provides isolation from the hot side so you don't die. If you have to ask how this circuit works, them you *definitely* need to use the sub-D connector!

0 Paul Canon over 5 years ago in reply to Keith Barkley

Prodigy 100 points

i'm designing a bluetooth based energy meter, so instead of having a db9 connector can i directly used RXD,TXD pins?

0 Keith Barkley over 5 years ago in reply to Paul Canon

Guru 42085 points

As long as the bluetooth circuit is totally contained inside the meter, yes.

0 Paul Canon over 5 years ago in reply to Keith Barkley

Prodigy 100 points

Thank You for your response

0 Keith Barkley over 5 years ago in reply to Paul Canon

Guru 42085 points

You should leave the isolation and DSUB circuitry there so that you can safely troubleshoot when the bluetooth does not work.

0 Paul Canon over 5 years ago in reply to Keith Barkley

Prodigy 100 points

Can't i use the SWDT pins for troubleshooting, debugging and calibrating?

0 Keith Barkley over 5 years ago in reply to Paul Canon

Guru 42085 points

Sure, but if you are unsure about the communication between the mcu and the bluetooth, you might want to sniff the serial.

0 Paul Canon over 5 years ago in reply to Keith Barkley

Prodigy 100 points

oh okay, Thank you so much or your insights, it was very helpful

0 JD Crutchfield over 5 years ago in reply to Paul Canon

TI__Mastermind 29105 points

Hey Paul,

As recommended in this thread, this is an isolation circuit for safety reasons. Basically, you don't want direct electrical connections between the "live" wire and the rest of your board. It could hurt your board but also electrically charge parts of your board you are not expecting or anything connected to the board (suck as a BLE sniffer as suggested before.

TI Isolation solutions can be found here and this looks to be the isolation forum: https://e2e.ti.com/support/isolation/f/1013

Good luck and stay safe!

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TIDM-MSP430AFE253SUBMETEREVM: Serial Communication Circuit