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Dear Ti :
I encountered some problems when using the ds90ub949a-q1 EVM. I hope I can get help from ti.
Background: I have a project that uses ds90ub949-q1 as the serializer on the soc side, in conjunction with the screen's 948 deserializer, to light up the lvds screen.
Problem: I have a problem when I use i2c and ti949-q1 on the soc side to communicate: when I first supply power to the ti949 adapter board and then to the soc development board, I cannot read the ti949 registers. But when I cut off the power to the ti949 and then re powered it, the registers that I used the i2c tool to operate it can be read again.
However, in my project, the i2c communication between soc and ti949 is to be placed in the driver code, but I cannot guarantee the loading order of ti949 and driver. This also leads to the fact that the 949 cannot interact with the i2c code in the driver to truly light up the screen.
Best Regards,
Xinyu
Hello Jaradat:
Allow me to elaborate on my question:
As shown in the figure below
i2C Master attached to Serializer
In this configuration, DS90UB949 evm acts as a slave on the local I 2 C bus and DS90UB948 will act as a master proxy on the remote i2c bus
I need to communicate with the 948 serializer on the screen through the 949evm serializer. Realize functions such as lighting the screen and controlling touch
The screen is now lit, but there is a problem with the touch function. My touch screen can be understood as the remote slave device in the figure, and I can already communicate with him. However, since my touch is implemented in the cyclic mode (and only in the cyclic mode), that is, I will continuously read the data of the touch device on the screen through the i2c link of 949+948. It was normal at first, but i2c read failed after a period of time.
At this time, both the 949 EVM reading and the remote slave reading failed.
I can only read the 949 evm register again by re powering down and re powering on the 949 evm
This is all my current registers:
Best Regards,
Xinyu
Hello Jaradat:
1.Do you mean that after powering your system up you can communicate locally between the I2C Master and the UB949, and through that to the UB948 into the Touch screen, but after some time you can't communicate anymore, either locally or remotely?! Is my understanding correct?
If the above is correct, how long is the waiting time from working to non-working?
>>>> Your understanding is correct. It took about 1 minute from working to not working
2.Are you doing any changes on the system during this time before it fails? Or you just keep cyclic reading? How often you do the reading?
>>>> During this period, I will not make changes to the system, but read the data returned from the touch screen circularly.
The reading time of each cycle is 20ms.
3.Once there is no more reading is possible, do you still see LOCK on the UB948？
>>>> If I want to control the UB949 again, I can only power off the UB949 and then power it on again
4.How do you recover this issue?
>>>> Because the above UB949 suddenly loses control, in order to control the UB948 and touch device again, when the UB949 is powered off, the entire system needs to be powered on again.
This is because when the EVM is powered off, it means that the video signal and the entire control link of I2c are interrupted
5.You said resting the UB949 will allow local communication again, but what about UB948 and Touch screen?
For your convenience, the following figure shows my overall display architecture
>>>> As shown in the figure above
UB948 is designed in the screen and controlled by its own MCU architecture. All communication with UB948 and Touch devices should be through UB949. After the UB949 is disconnected, it can no longer communicate with the UB948 and Touch devices
Best Regards,
Xinyu
Hello Jaradat,
I'm sorry to reply so late. Due to the overall design problem, 948 is designed on the screen, and I can't measure it. Because the I2c used by 949 EVM on the soc side is connected with multiple devices, the logic analyzer is not able to measure accurately.
But I found a way to improve. After the J9 jumper of EVM was pulled out, the above problems were improved a lot
This is the default setting. What is the reason?
Best Regards,
Xinyu
