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DS250DF230EVM: how to Clear PRBS Checker Error Count

jack Gao

Prodigy 10 points

Part Number: DS250DF230EVM
Other Parts Discussed in Thread: DS250DF230

We use DS250DF230EVM to test PRBS checker. But we can not Clear PRBS Checker Error Count following your "DS2x0DF810, DS250DFx10, DS250DF230 Programmer's Guide". we can reak PRBS ERR Counter, but we cannot clear the PRBS ERR Counter. Attached is our code. (we have set Channel correctly)

Thanks

Jack

set PRBS checker enable

regData = new SetRegisterData(0x0d, 0x80, 0x00);

registerData.Add(regData);

regData = new SetRegisterData(0x79, 0x40, 0x40);

registerData.Add(regData);

regData = new SetRegisterData(0x30, 0x08, 0x00);

registerData.Add(regData);

regData = new SetRegisterData(0x30, 0x08, 0x08);

registerData.Add(regData);

regData = new SetRegisterData(0x30, 0x10, 0x10);

registerData.Add(regData);

regData = new SetRegisterData(0x30, 0x10, 0x00);

registerData.Add(regData);

regData = new SetRegisterData(0x82, 0x40, 0x40);

registerData.Add(regData);

regData = new SetRegisterData(0x82, 0x40, 0x00);

registerData.Add(regData);

read PRBS ERR Counter

registerChannelRecord = new SetWriteReadRegisterData(writeCommand, 0x82, 0x80, 0x80);

registdatas.Add(registerChannelRecord);

registerChannelRecord = new SetWriteReadRegisterData(readCommand, 0x83, 0xff, 0xff);

registdatas.Add(registerChannelRecord);

registerChannelRecord = new SetWriteReadRegisterData(readCommand, 0x84, 0xff, 0xff);

registdatas.Add(registerChannelRecord);

registerChannelRecord = new SetWriteReadRegisterData(writeCommand, 0x82, 0x80, 0x00);

registdatas.Add(registerChannelRecord);

clear PRBS ERR Counter

registerChannelRecord = new SetWriteReadRegisterData(writeCommand, 0x82, 0x40, 0x40);

registdatas.Add(registerChannelRecord);

registerChannelRecord = new SetWriteReadRegisterData(writeCommand, 0x82, 0x40, 0x00);

registdatas.Add(registerChannelRecord);

over 4 years ago

0 Rodrigo Natal over 4 years ago

TI__Mastermind 19235 points

Related to: registerChannelRecord = new SetWriteReadRegisterData(writeCommand, 0x82, 0x40, 0x00

Can you confirm that the write value is 0x00 and the write mask is 0x40?

The routine per the programming guide works, TI have validated it extensively.

A couple of debug questions.

Is checker locking to the correct PRBS pattern as observed via retimer channel register 0x01?
What values are being observed on the PRBS checker retimer channel for channel registers 0x27, 0x28 and 0x78?

Table 54. Register Writes to Clear PRBS Checker Error Count

STEP

SHARED/ CHANNEL REGISTER SET

OPERATION

REGISTER ADDRESS [HEX]

REGISTER VALUE [HEX]

WRITE MASK [HEX]

COMMENT

1

Channel

Write

82

40

40

Reset PRBS counter

2

Channel

Write

82

00

40

Un-reset PRBS counter

Thanks,

Rodrigo Natal

0 jack Gao over 4 years ago in reply to Rodrigo Natal

Prodigy 10 points

Hi Rodrigo,

Following your questions:

register value
0x01 0xd2
0x27 0x11
0x28 0x6c
0x78 0x30

I can confirm that the write value is 0x00 and the write mask is 0x40.

public void ClearPRBSCheckerErrorCount(int address, int die, int channel, byte commandNumber)
{
SetRegisterData regData;
List<SetRegisterData> registerData = new List<SetRegisterData>();
regData = new SetRegisterData(0x82, 0x40, 0x40);
registerData.Add(regData);
regData = new SetRegisterData(0x82, 0x40, 0x00);
registerData.Add(regData);
USBOption.SetMaskRgisterValues((byte)address, (byte)die, (byte)(channel), commandNumber, registerData);
}
public SetRegisterData(byte address, byte mask, byte data,string remarks=null)
{
this.Address=address;
this.Mask=mask;
this.Data=data;
this.Remarks = remarks;
}
Thank you

0 Rodrigo Natal over 4 years ago in reply to jack Gao

TI__Mastermind 19235 points

Hi Jack,

With 01 =0xD2 this means PRBS pattern was detected and the pattern is PRBS9. Does that sound correct?

The retimer shows signal detected and CDR locked and the reported retimer eye opening values are good, thus I would have expected zero BER at the retimer PRBS checker.

Question: Can you provide a full retimer channel registers dump (i.e. read the retimer register values observed in your system) so that I can see all of the settings you are actually applying?

Thanks,

Rodrigo

0 jack Gao over 4 years ago in reply to Rodrigo Natal

Prodigy 10 points

Hi Rodrigo,

PRBS9 is correct. Normally, the BRE is 0, when I turn off the signal source, the biggest BRE is 2047. Now I want to clear it, but BRE keeps 2047. When I re-initial it, the BRE is 0;

Could you please give me your email address?

Thanks

Jack

0 Rodrigo Natal over 4 years ago in reply to jack Gao

TI__Mastermind 19235 points

Hi,

Please try the below, and see if it solves the issue.

Make sure to un-freeze the PRBS error counter after reading
If you get into error condition with count = 2047 you may need to "Re-Load PRBS Checker Pattern Match". See retimer register routine below

Table. Register Writes to Re-Load PRBS Checker Pattern Match

STEP	SHARED/ CHANNEL REGISTER SET	OPERATION	REGISTER ADDRESS [HEX]	REGISTER VALUE [HEX]	WRITE MASK [HEX]	COMMENT
1	Channel	Write	30	00	08	Set prbs_en_dig_clk=0 to disable the digital clock
2	Channel	Write	30	08	08	Set prbs_en_dig_clk=1 to enable the digital clock
3	Channel	Write	30	10	10	Force reload of PRBS checker seed
4	Channel	Write	30	00	10	Undo force reload of PRBS checker seed
5	Channel	Write	82	40	40	Reset PRBS counters
6	Channel	Write	82	00	40	Un-reset PRBS counters
7	Channel	Read	01			Read PRBS status: Reg_0x01[6]: PRBS pattern polarity detection 1’b0: Polarity detected is not inverted 1’b1: Polarity detected is inverted Reg_0x01[4]: PRBS sequence detected 1’b1: Pattern detected 1’b0: No pattern detected Reg_0x01[3:1]: PRBS detect result 3’b000: PRBS7 3’b001: PRBS9 3’b010: PRBS11 3’b011: PRBS15 3’b100: PRBS23 3’b101: PRBS31 3’b110: PRBS58 3’b111: PRBS63

0 jack Gao over 4 years ago in reply to Rodrigo Natal

Prodigy 10 points

Yes, I know that. But why 2047 can not use simply clear BRE,? Reload patterns needs more time. Another question, How can I accumulate PRBS for a long time without losing PRBS ERR Count as little as possible?

0 Rodrigo Natal over 4 years ago in reply to jack Gao

TI__Mastermind 19235 points

You should be able to run the retimer PRBS checker indefinitely as long as the PRBS pattern doesn't change.

Thanks,

0 jack Gao over 4 years ago in reply to Rodrigo Natal

Prodigy 10 points

I mean, before I read the BRC, it has reached 2047, which means that a part of the count value has been lost. How to ensure that the BRC is read before it reaches 2047?

0 Rodrigo Natal over 4 years ago in reply to jack Gao

TI__Mastermind 19235 points

The clear PRBS checker sequence per the programming guide should clear the errors. if errors max out again do to PRBS checker losing lock/sync then the only other option is to perform the "reload PRBS checker match" sequence.

Rodrigo Natal

0 jack Gao over 4 years ago in reply to Rodrigo Natal

Prodigy 10 points

Do you have any suggestions on how long to read the BRC？

Jack

0 Rodrigo Natal over 4 years ago in reply to jack Gao

TI__Mastermind 19235 points

The PRBS test duration would depend on what BER level you are verifying for. As example, assume BER target is 1E-12 with data rate of 25.78125Gbps.

To reach that target, you would need to observe no more than a single error per 1E+12 bits transmit
A single iteration of 1E+12 bits takes around 39 seconds i.e. 1E12 bits/(25.78125Gb/s)
For statistical confidence you want to run 3 or more iterations of 1E+12 or 3E+12 bits. The PRBS checker test duration for that is ~3*39 seconds or around 2 minutes

Thanks,

Rodrigo Natal