BQ76PL455A: Communication of BQ76PL455A

Jet Lee

Prodigy 170 points

Part Number: BQ76PL455A

Hi,

Our MCU provide +5V for BQ76PL455A. The RX and TX signal as following.

Yellow: BQ76PL455A RX

Blue: BQ76PL455A TX

The high level of TX is about +4V and low level is 0.4~0.6V. Is it normal?

Best Regards,

Jet

over 5 years ago

0 Vince over 5 years ago

TI__Mastermind 19775 points

Hi Jet,

This is not normal behavior. Would you be able to confirm that the switches on SW2 of the EVM are both in the single-ended mode on the PL455 device connected to the microcontroller?

Thanks!
Vince

0 Jet Lee over 5 years ago in reply to Vince

Prodigy 170 points

Hi, Vince

Yes, the SW2 switch to Signal-End always. We measure the Pin52(C = 5V) and Pin53 (D=0V).

The Pin38(TX) does not connect to SW2.

Best Regards,

Jet

0 Vince over 5 years ago in reply to Jet Lee

TI__Mastermind 19775 points

Hi Jet,

Could you also confirm that the VIO and VCC voltage values match on the board and from the microcontroller? The mismatched voltage levels of the communications signals would imply the communications voltage supplies are not correctly matched.

Regards,
Vince

0 Jet Lee over 5 years ago in reply to Vince

Prodigy 170 points

Hi Vince,

Pin41(VIO = 4.75V) and VCC=5.0V

Best Regards,
Jet

0 Roger Hwang over 5 years ago in reply to Jet Lee

TI__Genius 10785 points

Jet,
Can you share Uart portion of schematics?

0 Roger Hwang over 5 years ago in reply to Roger Hwang

TI__Genius 10785 points

Jet,
Is problem soleved?
I want to see GND between MCU and PL455A.
Check the gnding and shows us Uart portion of schematic.

0 Jet Lee over 5 years ago in reply to Roger Hwang

Prodigy 170 points

0 Roger Hwang over 5 years ago in reply to Jet Lee

TI__Genius 10785 points

Hi Jet,

Are you connecting uC directly to PL455A evm?

Can you show me how you connect VDDX and VIO of PL455A EVM?

0 Jet Lee over 5 years ago in reply to Roger Hwang

Prodigy 170 points

0 Vince over 5 years ago in reply to Jet Lee

TI__Mastermind 19775 points

Hi Jet,

I am unable to replicate your issue with a 12V to 22V supply attached to the PL455 EVM (from BAT0 to BAT16), 5.13V applied for VCC, and standard UART communications to the device:

Please provide further info on the power source you are using for the PL455.

Regards,

Vince

Power management

Power management forum

BQ76PL455A: Communication of BQ76PL455A