DS90UB948-Q1: DS90UB948-Q1: GPIO8 was pull high when Lock with serializer

ming zhou

Part Number: DS90UB948-Q1

Hi TI Team

As shown in the picture. When Ser and Des are locked, GPIO8 will be pulled high. The process from low to high in the red is the process of our SW configuration, but the red part in front is the state where DS90UB948 GPIO8 is pulled high by itself. How can I design it to pull the red box stage low? I have added a pull-down resistor in the schematic, but this problem still cannot be avoided.

I have also shown the SW configuration, please help review it, and please notify me in time if there are any SW configuration issues.

8 天前

0 Vivian Gao 7 天前

TI__Mastermind 38080 points

参考下方链接的回复。

(+) DS90UB948-Q1: ds90ub948 GPIO8 输出高电平 - 接口论坛 - 接口 - E2E 设计支持

(+) DS90UB948-Q1: DS90UB948 GPIO8口输出高电平 - 接口论坛 - 接口 - E2E 设计支持

0 ming zhou 7 天前回复 Vivian Gao

Prodigy 10 points

The two links posted do not solve the problem of why GPIO8 outputs high in the default state 0x21=00

0 Vivian Gao 7 天前回复 ming zhou

TI__Mastermind 38080 points

GPIO8_REG defaults to I2S_CLK functionality per datasheet register 0x21 = 0x0.

This will be either pulled high or have a clock signal, depending on what the DES is locked onto. So what is happening here is that when it defaults to I2S functionality it goes high then when customer programs it to GPIO functionality it pulls it low so it appears like a high/low pulse.

If customer is able to program 948 locally before lock with the SER then they can override this pin to GPIO mode prior to establishing lock with Ser or can they program the DES remotely when there is link (but no lock), so that the GPIO is programmed to GPIO mode before lock has been established.

0 ming zhou 7 天前回复 Vivian Gao

Prodigy 10 points

"can they program the DES remotely when there is link (but no lock), so that the GPIO is programmed to GPIO mode before lock has been established" How to operate this solution

0 ming zhou 7 天前回复 Vivian Gao

Prodigy 10 points

how to do this operation? "can they program the DES remotely when there is link (but no lock), so that the GPIO is programmed to GPIO mode before lock has been established."

0 Vivian Gao 7 天前回复 ming zhou

TI__Mastermind 38080 points

Once the DES powers up (PDB high) you need to immediately set the GPIO to input or output Low.

The SER is able to talk to the DES remotely so once PDB is high on the DES, you need to immediately reprogram the DES GPIO.

Now you need to make sure when you configure GPIO8 on the DES , the DES has power (PDB = high) otherwise the command will not go through.

0 ming zhou 7 天前回复 Vivian Gao

Prodigy 10 points

Please provide the corresponding register configuration.

0 Vivian Gao 7 天前回复 ming zhou

TI__Mastermind 38080 points

You need to set those GPIO to a specific state after I2C passthrough command

for instance ... after bit3 of register 0x3 of the SER is enabled you'll get remote I2C communication to DES, immeditaly override for example register 0x21 of the DES to 0x30 (board.WriteI2C(DES_Addr,0x21,0x30) to put GPIO8 to output mode that should solve the issue.