DS90UB941AS-Q1: FREQ_HIGH Register (Address = 0x5E) setting

Ryan Wang

Part Number: DS90UB941AS-Q1

Tool/software:

Team,

FREQ_HI_THR is only 7bit. The max number is 0x7F. But customer DSI frequency is 440MHz. What might happen if DSI freq> FREQ_HI_THR?

Thanks

3 months ago

0 Nikolas Antonucci 3 months ago

TI__Mastermind 21485 points

Hi Ryan,

Who is the tier 1 and OEM?

Please refer to Ben's second response in this E2E thread: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1047558/ds90ub941as-q1-freq_high-register-address-0x5e

Best,

Nikolas

0 Ryan Wang 3 months ago in reply to Nikolas Antonucci

TI__Expert 7455 points

Nikolas,

Tier1 is YinWang

OEM is Seres

Thanks for link.

"If the frequency is above the high threshold, the freq_high output is asserted. If the frequency is below the low threshold, the freq_low output is asserted"

I don't understand what does "freq_high output is asserted" mean? Could you point which section in datasheet for this?

And FREQ_HI_THR is for PCLK or DSI freq? 0x7F cannot cover max PCLK 210MHz, DSI 630MHz.

0 Nikolas Antonucci 3 months ago in reply to Ryan Wang

TI__Mastermind 21485 points

Hi Ryan,

FREQ_LO_THR and FREQ_HI_THR are the threshold limits for DSI_CLK_DET (0x5A[3]) and NO_DSI_CLK (0x5A[1]).

Both thresholds are in terms of DSI frequency.

Best,

Nikolas

0 Ryan Wang 3 months ago in reply to Nikolas Antonucci

TI__Expert 7455 points

Nikolas,

Max value for FREQ_HI_THR is 0x7F. Customer DSI is 440MHz. But we still see DSI_CLK_DET (0x5A[3]) valid and no NO_DSI_CLK (0x5A[1]). Why is that?

0 Nikolas Antonucci 3 months ago in reply to Ryan Wang

TI__Mastermind 21485 points

Hi Ryan,

This makes sense.

If the frequency is above the FREQ_HI_THR value, then DSI_CLK_DET is asserted. If the frequency is below the FREQ_LO_THR value, then NO_DSI_CLK is asserted.

FREQ_HI_THR = 0x7F corresponds with 127MHz and FREQ_LO_THR = 0x06 corresponds with 6MHz. Since 127MHz > FREQ_HI_THR, DSI_CLK_DET will be asserted. Since 127MHz is not < 6MHz, NO_DSI_CLK is not asserted.

The default settings should be okay to use.

Best,

Nikolas

0 Ryan Wang 3 months ago in reply to Nikolas Antonucci

TI__Expert 7455 points

Nikolas,

Understand now

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DS90UB941AS-Q1: FREQ_HIGH Register (Address = 0x5E) setting