TPS23881: Channel x VOLTAGE register

Hi, 

Thank you for your question. 

The PoE applications engineering team is currently out of the office at this time and will respond to your post by end of day Monday, 6/15. 

Best Regards, 

Brett Colteaux

PoE Product Marketing Engineer

Louis,

Did you load firmware to TPS23881? Please make sure you load the latest 0x05 firmware to TPS23881 devices. You can download the TPS23881 firmware from TPS23881 product folder. Thanks.

Best regards,

Penny

Hi Penny

I Read firmware version.(addr 0x41)

The SRAM Revision value is 0x0.

I checked the TPS23881 product folder to update the firmware, but I don't have the permission as shown below.

and Please provide detailed instructions on how to update the firmware.

Best regards

Hi Louis,

Please request access through TPS23882 product folder  (ti.com has gone through some changes recently and the note it missing from TPS23881 product folder. we will add links back to TPS23881 folder)and we will grant your access today. Thanks. 

Best regards,

Penny

Hi Penny

Thanks for your support

We downloaded the firmware using the TPS23881 GUI and checked 0x0505.

However, when I turn the power off and on again, it changes to 0x0.

1. Why is it not saved?

2. Can you provide example code to load SRAM and Parity Code for the document below? (C Code)

Best regards

Louis,

By SRAM's definition, it is not saved after power off: SRAM (static RAM) is random access memory (RAM) that retains data bits in its memory as long as power is being supplied.

So at each power up, you have to load the SRAM code to TPS23881 devices. We have a tech note and MSP430 reference code  you can refer to. Thanks. 

Best regards,

penny

Hi penny

Thanks, I understood your answer.

I have Additional Question.

1. Is there a way to keep data in memory even when the power is off? (ex: Write to ROM)

2. The maximum I2C CLK is mark as 400Khz on Datasheet.

What is the maximum rate of I2C for program the data to SRAM for reliably?

Best regards.

Hi Louis,

Please see my answers below. Thanks. 

1. Is there a way to keep data in memory even when the power is off? (ex: Write to ROM)

[Penny]No. This how TPS23881 is design to have flexibility to make firmware patches for bug fixes and feature adding. 

2. The maximum I2C CLK is mark as 400Khz on Datasheet.

What is the maximum rate of I2C for program the data to SRAM for reliably?

[Penny]The I2C spec applies for both normal register configurations and SRAM load. 

Best regards,

Penny

Hi Penny

I loaded TPS23881 with the latest 0x05 firmware.

but this issue was not resolve.

Only the frequency of occurrence has been reduced.

The below log data shows that the current of Port0 rose to 5.28A.

Please respond quickly.

Best regards.

Hi Louis,

Looks like the voltage reading issue is fixed. How did you read the port current? 

If you use configuration A mode(8 bit I2C read and write) you will need to read 2 bytes from current register at the same time. If you use configuration B mode(16 bit I2C read and write), you will need to read 4 bytes from current register at the same time. 

Best regards,

Penny

Hi Penny

I use Configuration A mode and Non - Parametric Read Cycle.

0x30h Channel 1 Current LSByte (1Byte)

0x31h Channel 1 Current MSByte(bits 13 to 8)

Do I need to read 2 bytes at a time with the Parametric Read Cycle?

When using Parametric Read Cycle, is it necessary to set nbitACC to 1?

Best regards.

Hi Louis,

When reading voltage and current registers(especially current registers), you will need to read 2 bytes at the same time to ensure you get the values from one measurement. 

Please refer to MSP430 reference code on ti.com (https://www.ti.com/product/TPS23881#design-development##software-development). Thanks. 

Best regards,

Penny

Hi penny

Thanks for your support.

I have additional Inquiries

There is an issue in which abnormal operation occurs when the firmware is downloaded twice in SRAM.

First Download.(Normal)

Second Download(Abnormal)

In case of abnormal operation, reset the power and download the firmware to operate normally.

Why is it operating abnormally when I download the firmware twice?

Best Regards