DS90UB941AS-Q1: How to be setting TSKIP_CNT value to register by the calculation formula

SUNGHYUN PARK

Prodigy 20 points

Part Number: DS90UB941AS-Q1

Hi All,

I have the question for setting TSKIP_CNT value to Register by the calculation formula below.

TSKI_CNT = Round(65xfDSI - 5)

where fDSI is the DSI clock frequency in GHz. and the above formula is 24 page of DS90UB941AS-Q1 document.

If DSI Frequency is 24.4Mhz, TSKI_CNT value is -3.544 by the above formula.

So how do it set this value to DSI indirect Register?

Please let me know how to be setting.

Thanks,

BRs,

Sunghyun

over 1 year ago

0 Fadi Abdulhameed over 1 year ago

TI__Mastermind 29815 points

Hi Sunghyun,

I will review and get back to you tomorrow.

Regards,
Fadi A.

0 Hamzeh Jaradat over 1 year ago in reply to Fadi Abdulhameed

TI__Guru** 108420 points

Hello Sunghyun,

Please refer to the following Applications note, section 4.

www.ti.com/.../snla356.pdf

0 SUNGHYUN PARK over 1 year ago in reply to Hamzeh Jaradat

Prodigy 20 points

Hi All,

It was only mentioned about the calculation formula and setting to Register in the above document.

My question is that how to set the calculated result value to Register.

If the calculated result value is positive, it should set as the above document.

But If the calculated result value is negative, how do this value set to Register?

for example, if the calculated result value is -3.544, I wonder that it should be set as the following.

write_i2c(0x40, 0x04)

write_i2c(0x41,05)

write_i2c(0x42,0x04)

Please check about the above register setting values.

If there is the wrong value, Please let me know.

Thanks.

BRs,

Sunghyun

0 Fadi Abdulhameed over 1 year ago in reply to SUNGHYUN PARK

TI__Mastermind 29815 points

Hello Sunghyun,

You need to calculate the DSI frequency based on this equation in the datasheet

Assuming 4 lanes for DSI.

fDSI = PCLK*12/4

fDSI = 24.4MHz * 12/4 = 73.2 MHz

TSKIP_CNT = Round(65*0.0732GHz - 5) = 0

So DSI Indirect Register 0x5 "DPHY_SKIP_TIMING" should be 0x5 = 0x0.

write_i2c(0x40, 0x04)

write_i2c(0x41,05)

write_i2c(0x42,0x0)

Regards,
Fadi A.

0 SUNGHYUN PARK over 1 year ago in reply to Fadi Abdulhameed

Prodigy 20 points

Hi Fadi A,

thanks for the detailed explanation and your support.

BRs,

Sunghyun

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DS90UB941AS-Q1: How to be setting TSKIP_CNT value to register by the calculation formula