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DAC38J84: DAC Alarms at High Speed

Pavan
Intellectual 670 points
Part Number: DAC38J84
Other Parts Discussed in Thread: LMK04826

Hi


We are having an issue with the DAC38J84.

FPGA                   ---  Virtex 7
Clock Generator  ---  LMK04826
DAC                     ---  DAC38J84

In the DAC34J84, there are some Error / Alarm indications


a. 8b/10b Disparity error
b. 8b/10b Not in table code error
c. Code Synchronization error
d. Elastic Buffer Overflow error
e. Link Configuration error
f.  Frame Alignment error
g. Multiframe Alignment error
h. FIFO Full
i.  FIFO Empty

 

We are configuring DAC in two modes

1. At Low Speed 312.5 MSPS Sampling rate.
2. At High Speed 2.5 GSPS Sampling rate.

Case 1 : Low Speed

SERDES Rate                       = 6.25 Gbps
LMK Clk Frequency to FPGA   = 156.25 MHz (SERDES Rate / 40)
LMK Clk Frequency to DAC    = 312.50 MHz
SYSREF Frequency               = 4.8828125 MHz (FPGA Clk / 64)
Interpolation                       = x 1
Output Data from DAC         = Singletone 25 MHz

 

We are measuring the clock coming to FPGA and DAC. They are as per specs.
At low Speed, we are able to capture the correct data from DAC.
JESD Link up is done and there are NO ALARMS in DAC.

Case 2 : High Speed

SERDES Rate                      = 6.25 Gbps
LMK Clk Frequency to FPGA  = 156.25 MHz (SERDES Rate / 40)
LMK Clk Frequency to DAC   = 2.5 GHz
SYSREF Frequency              = 4.8828125 MHz (FPGA Clk / 64)
Interpolation                      = x 8
Output Data from DAC        = Singletone 25 MHz

 

We are measuring the clock coming to FPGA and DAC. They are as per specs.
At High Speed, we are unable to capture the correct data from DAC.
JESD Sync Signal is continuously toggling and there are ALARMS in DAC.

 

We are getting the following ALARM / Error indications at High Speed
a. 8b/10b Disparity error
b. 8b/10b Not in table code error
c. Code Synchronization error
d. Elastic Buffer Overflow error
e. Frame Alignment error
f. Multiframe Alignment error
g. FIFO Full
h. FIFO Empty

 

These errors indicate that there is problem with JESD Link up at high speed.

It would be helpful if you guide us to resolve this issue

Please Find Attachments :

1. LMK Configuration files at Low and High speeds
2. DAC Configuration files at Low and High Speeds
3. DAC Outputs at Low speed

8231.LMK1_LOW_SPEED.txt 
R0 (INIT)	0x000090
R0	0x000010
R2	0x000200
R3	0x000306
R4	0x0004D0
R5	0x00055B
R6	0x000600
R12	0x000C51
R13	0x000D04
R256	0x010008
R257	0x010155
R258	0x010255
R259	0x010301
R260	0x010422
R261	0x010500
R262	0x0106F0
R263	0x010755
R264	0x010808
R265	0x010955
R266	0x010A55
R267	0x010B01
R268	0x010C22
R269	0x010D00
R270	0x010EF0
R271	0x010F55
R272	0x011008
R273	0x011155
R274	0x011255
R275	0x011301
R276	0x011422
R277	0x011500
R278	0x0116F0
R279	0x011755
R280	0x011810
R281	0x011955
R282	0x011A55
R283	0x011B01
R284	0x011C22
R285	0x011D00
R286	0x011EF0
R287	0x011F11
R288	0x012010
R289	0x012155
R290	0x012255
R291	0x012301
R292	0x012422
R293	0x012500
R294	0x0126F0
R295	0x012711
R296	0x012810
R297	0x012955
R298	0x012A55
R299	0x012B01
R300	0x012C22
R301	0x012D00
R302	0x012EF0
R303	0x012F11
R304	0x013019
R305	0x013155
R306	0x013255
R307	0x013301
R308	0x013402
R309	0x013500
R310	0x0136F1
R311	0x013701
R312	0x013820
R313	0x013903
R314	0x013A02
R315	0x013B00
R316	0x013C00
R317	0x013D08
R318	0x013E03
R319	0x013F00
R320	0x01408B
R321	0x014100
R322	0x014200
R323	0x014311
R324	0x0144FF
R325	0x01457F
R326	0x014618
R327	0x01471A
R328	0x014802
R329	0x014942
R330	0x014A02
R331	0x014B16
R332	0x014C00
R333	0x014D00
R334	0x014EC0
R335	0x014F7F
R336	0x015003
R337	0x015102
R338	0x015200
R339	0x015300
R340	0x015478
R341	0x015500
R342	0x015678
R343	0x015700
R344	0x015896
R345	0x015900
R346	0x015A78
R347	0x015BD4
R348	0x015C20
R349	0x015D00
R350	0x015E00
R351	0x015F0B
R352	0x016000
R353	0x016101
R354	0x0162A4
R355	0x016300
R356	0x016400
R357	0x01650A
R369	0x0171AA
R370	0x017202
R380	0x017C18
R381	0x017D77
R358	0x016600
R359	0x016700
R360	0x016805
R361	0x016959
R362	0x016A20
R363	0x016B00
R364	0x016C00
R365	0x016D00
R366	0x016E13
R371	0x017300
R8189	0x1FFD00
R8190	0x1FFE00
R8191	0x1FFF53

5516.LMK1_HI_SPEED.txt 
R0 (INIT)	0x000090
R0	0x000010
R2	0x000200
R3	0x000306
R4	0x0004D0
R5	0x00055B
R6	0x000600
R12	0x000C51
R13	0x000D04
R256	0x010001
R257	0x010155
R258	0x010255
R259	0x010301
R260	0x010422
R261	0x010500
R262	0x0106F0
R263	0x010755
R264	0x010801
R265	0x010955
R266	0x010A55
R267	0x010B01
R268	0x010C22
R269	0x010D00
R270	0x010EF0
R271	0x010F55
R272	0x011001
R273	0x011155
R274	0x011255
R275	0x011301
R276	0x011422
R277	0x011500
R278	0x0116F0
R279	0x011755
R280	0x011810
R281	0x011955
R282	0x011A55
R283	0x011B01
R284	0x011C22
R285	0x011D00
R286	0x011EF0
R287	0x011F11
R288	0x012010
R289	0x012155
R290	0x012255
R291	0x012301
R292	0x012422
R293	0x012500
R294	0x0126F0
R295	0x012711
R296	0x012810
R297	0x012955
R298	0x012A55
R299	0x012B01
R300	0x012C22
R301	0x012D00
R302	0x012EF0
R303	0x012F11
R304	0x013019
R305	0x013155
R306	0x013255
R307	0x013301
R308	0x013402
R309	0x013500
R310	0x0136F1
R311	0x013701
R312	0x013820
R313	0x013903
R314	0x013A02
R315	0x013B00
R316	0x013C00
R317	0x013D08
R318	0x013E03
R319	0x013F00
R320	0x01408B
R321	0x014100
R322	0x014200
R323	0x014311
R324	0x0144FF
R325	0x01457F
R326	0x014618
R327	0x01471A
R328	0x014802
R329	0x014942
R330	0x014A02
R331	0x014B16
R332	0x014C00
R333	0x014D00
R334	0x014EC0
R335	0x014F7F
R336	0x015003
R337	0x015102
R338	0x015200
R339	0x015300
R340	0x015478
R341	0x015500
R342	0x015678
R343	0x015700
R344	0x015896
R345	0x015900
R346	0x015A78
R347	0x015BD4
R348	0x015C20
R349	0x015D00
R350	0x015E00
R351	0x015F0B
R352	0x016000
R353	0x016101
R354	0x0162A4
R355	0x016300
R356	0x016400
R357	0x01650A
R369	0x0171AA
R370	0x017202
R380	0x017C18
R381	0x017D77
R358	0x016600
R359	0x016700
R360	0x016805
R361	0x016959
R362	0x016A20
R363	0x016B00
R364	0x016C00
R365	0x016D00
R366	0x016E13
R371	0x017300
R8189	0x1FFD00
R8190	0x1FFE00
R8191	0x1FFF53

DAC_configurations_Low_speed.txt 
# DAC configuration 
# 442 with x1 Interpolation Low Speed

dac_address: 0x0    dac_data : 0x258
dac_address: 0x1    dac_data : 0x3
dac_address: 0x2    dac_data : 0x2082
dac_address: 0x3    dac_data : 0xA300
dac_address: 0x4    dac_data : 0xF0F0
dac_address: 0x5    dac_data : 0xFF07
dac_address: 0x6    dac_data : 0xFFFF
dac_address: 0x7    dac_data : 0x3100
dac_address: 0x8    dac_data : 0x0
dac_address: 0x9    dac_data : 0x0
dac_address: 0xA    dac_data : 0x0
dac_address: 0xB    dac_data : 0x0
dac_address: 0xC    dac_data : 0x400
dac_address: 0xD    dac_data : 0x400
dac_address: 0xE    dac_data : 0x400
dac_address: 0xF    dac_data : 0x400
dac_address: 0x10   dac_data : 0x0
dac_address: 0x11   dac_data : 0x0
dac_address: 0x12   dac_data : 0x0
dac_address: 0x13   dac_data : 0x0
dac_address: 0x14   dac_data : 0x0
dac_address: 0x15   dac_data : 0x0
dac_address: 0x16   dac_data : 0x0
dac_address: 0x17   dac_data : 0x0
dac_address: 0x18   dac_data : 0x0
dac_address: 0x19   dac_data : 0x0
dac_address: 0x1A   dac_data : 0x20
dac_address: 0x1B   dac_data : 0x0
dac_address: 0x1E   dac_data : 0x9999
dac_address: 0x1F   dac_data : 0x9980
dac_address: 0x20   dac_data : 0x8008
dac_address: 0x22   dac_data : 0x1B1B
dac_address: 0x23   dac_data : 0x1FF
dac_address: 0x24   dac_data : 0x20
dac_address: 0x25   dac_data : 0x4000
dac_address: 0x26   dac_data : 0x0
dac_address: 0x2D   dac_data : 0x1
dac_address: 0x2E   dac_data : 0xFFFF
dac_address: 0x2F   dac_data : 0x4
dac_address: 0x30   dac_data : 0x0
dac_address: 0x31   dac_data : 0x1000
dac_address: 0x32   dac_data : 0x0
dac_address: 0x33   dac_data : 0x0
dac_address: 0x34   dac_data : 0x0
dac_address: 0x3B   dac_data : 0x1800
dac_address: 0x3C   dac_data : 0x228
dac_address: 0x3D   dac_data : 0x88
dac_address: 0x3E   dac_data : 0x108
dac_address: 0x3F   dac_data : 0x0
dac_address: 0x46   dac_data : 0x1882
dac_address: 0x47   dac_data : 0x1C8
dac_address: 0x48   dac_data : 0x3143
dac_address: 0x49   dac_data : 0x0
dac_address: 0x4A   dac_data : 0xF1E
dac_address: 0x4B   dac_data : 0x801
dac_address: 0x4C   dac_data : 0x903
dac_address: 0x4D   dac_data : 0x300
dac_address: 0x4E   dac_data : 0xF0F
dac_address: 0x4F   dac_data : 0x1C61
dac_address: 0x50   dac_data : 0x0
dac_address: 0x51   dac_data : 0xDC
dac_address: 0x52   dac_data : 0xFF
dac_address: 0x53   dac_data : 0x0
dac_address: 0x54   dac_data : 0xFC
dac_address: 0x55   dac_data : 0xFF
dac_address: 0x56   dac_data : 0x0
dac_address: 0x57   dac_data : 0xFF
dac_address: 0x58   dac_data : 0xFF
dac_address: 0x59   dac_data : 0x0
dac_address: 0x5A   dac_data : 0xFF
dac_address: 0x5B   dac_data : 0xFF
dac_address: 0x5C   dac_data : 0x1133
dac_address: 0x5E   dac_data : 0x0
dac_address: 0x5F   dac_data : 0x3210
dac_address: 0x60   dac_data : 0x5764
dac_address: 0x61   dac_data : 0x211
dac_address: 0x64   dac_data : 0x1
dac_address: 0x65   dac_data : 0x1
dac_address: 0x66   dac_data : 0x1
dac_address: 0x67   dac_data : 0x1
dac_address: 0x68   dac_data : 0x7709
dac_address: 0x69   dac_data : 0x0
dac_address: 0x6A   dac_data : 0x0
dac_address: 0x6B   dac_data : 0xBD07
dac_address: 0x6C   dac_data : 0x7
dac_address: 0x6D   dac_data : 0x90
dac_address: 0x6E   dac_data : 0x0
dac_address: 0x6F   dac_data : 0x0
dac_address: 0x70   dac_data : 0x0
dac_address: 0x71   dac_data : 0x0
dac_address: 0x72   dac_data : 0x0
dac_address: 0x73   dac_data : 0x0
dac_address: 0x74   dac_data : 0x0
dac_address: 0x75   dac_data : 0x0
dac_address: 0x76   dac_data : 0x0
dac_address: 0x77   dac_data : 0x0
dac_address: 0x78   dac_data : 0x0
dac_address: 0x79   dac_data : 0x0
dac_address: 0x7A   dac_data : 0x0
dac_address: 0x7B   dac_data : 0x0
dac_address: 0x7C   dac_data : 0x0
dac_address: 0x7D   dac_data : 0x0
dac_address: 0x3B   dac_data : 0x0
dac_address: 0x25   dac_data : 0x0
dac_address: 0x3C   dac_data : 0x250
dac_address: 0x3C   dac_data : 0x50
dac_address: 0x3E   dac_data : 0x128
dac_address: 0x4C   dac_data : 0x903
dac_address: 0x4D   dac_data : 0x300
dac_address: 0x4B   dac_data : 0x801
dac_address: 0x4D   dac_data : 0x300
dac_address: 0x4E   dac_data : 0xF0F
dac_address: 0x0    dac_data : 0x18

DAC_configurations_High_speed.txt 
# DAC configuration 
# 442 with x8 Interpolation High Speed

dac_address : 0x0    dac_data : 0x418
dac_address : 0x1    dac_data : 0x3
dac_address : 0x2    dac_data : 0x2082
dac_address : 0x3    dac_data : 0xA300
dac_address : 0x4    dac_data : 0xF0F0
dac_address : 0x5    dac_data : 0xFF07
dac_address : 0x6    dac_data : 0xFFFF
dac_address : 0x7    dac_data : 0x3100
dac_address : 0x8    dac_data : 0x0
dac_address : 0x9    dac_data : 0x0
dac_address : 0xA    dac_data : 0x0
dac_address : 0xB    dac_data : 0x0
dac_address : 0xC    dac_data : 0x400
dac_address : 0xD    dac_data : 0x400
dac_address : 0xE    dac_data : 0x400
dac_address : 0xF    dac_data : 0x400
dac_address : 0x10   dac_data : 0x0
dac_address : 0x11   dac_data : 0x0
dac_address : 0x12   dac_data : 0x0
dac_address : 0x13   dac_data : 0x0
dac_address : 0x14   dac_data : 0x0
dac_address : 0x15   dac_data : 0x0
dac_address : 0x16   dac_data : 0x0
dac_address : 0x17   dac_data : 0x0
dac_address : 0x18   dac_data : 0x0
dac_address : 0x19   dac_data : 0x0
dac_address : 0x1A   dac_data : 0x20
dac_address : 0x1B   dac_data : 0x0
dac_address : 0x1E   dac_data : 0x9999
dac_address : 0x1F   dac_data : 0x9980
dac_address : 0x20   dac_data : 0x8008
dac_address : 0x22   dac_data : 0x1B1B
dac_address : 0x23   dac_data : 0x1FF
dac_address : 0x24   dac_data : 0x20
dac_address : 0x25   dac_data : 0x4000
dac_address : 0x26   dac_data : 0x0
dac_address : 0x2D   dac_data : 0x1
dac_address : 0x2E   dac_data : 0xFFFF
dac_address : 0x2F   dac_data : 0x4
dac_address : 0x30   dac_data : 0x0
dac_address : 0x31   dac_data : 0x1000
dac_address : 0x32   dac_data : 0x0
dac_address : 0x33   dac_data : 0x0
dac_address : 0x34   dac_data : 0x0
dac_address : 0x3B   dac_data : 0x1800
dac_address : 0x3C   dac_data : 0x228
dac_address : 0x3D   dac_data : 0x88
dac_address : 0x3E   dac_data : 0x108
dac_address : 0x3F   dac_data : 0x0
dac_address : 0x46   dac_data : 0x1882
dac_address : 0x47   dac_data : 0x1C8
dac_address : 0x48   dac_data : 0x3143
dac_address : 0x49   dac_data : 0x0
dac_address : 0x4A   dac_data : 0xF1E
dac_address : 0x4B   dac_data : 0x801
dac_address : 0x4C   dac_data : 0x903
dac_address : 0x4D   dac_data : 0x300
dac_address : 0x4E   dac_data : 0xF0F
dac_address : 0x4F   dac_data : 0x1C61
dac_address : 0x50   dac_data : 0x0
dac_address : 0x51   dac_data : 0xDC
dac_address : 0x52   dac_data : 0xFF
dac_address : 0x53   dac_data : 0x0
dac_address : 0x54   dac_data : 0xFC
dac_address : 0x55   dac_data : 0xFF
dac_address : 0x56   dac_data : 0x0
dac_address : 0x57   dac_data : 0xFF
dac_address : 0x58   dac_data : 0xFF
dac_address : 0x59   dac_data : 0x0
dac_address : 0x5A   dac_data : 0xFF
dac_address : 0x5B   dac_data : 0xFF
dac_address : 0x5C   dac_data : 0x1133
dac_address : 0x5E   dac_data : 0x0
dac_address : 0x5F   dac_data : 0x3210
dac_address : 0x60   dac_data : 0x5764
dac_address : 0x61   dac_data : 0x211
dac_address : 0x64   dac_data : 0x1
dac_address : 0x65   dac_data : 0x1
dac_address : 0x66   dac_data : 0x1
dac_address : 0x67   dac_data : 0x1
dac_address : 0x68   dac_data : 0x7709
dac_address : 0x69   dac_data : 0x0
dac_address : 0x6A   dac_data : 0x0
dac_address : 0x6B   dac_data : 0xBD07
dac_address : 0x6C   dac_data : 0x7
dac_address : 0x6D   dac_data : 0x90
dac_address : 0x6E   dac_data : 0x0
dac_address : 0x6F   dac_data : 0x0
dac_address : 0x70   dac_data : 0x0
dac_address : 0x71   dac_data : 0x0
dac_address : 0x72   dac_data : 0x0
dac_address : 0x73   dac_data : 0x0
dac_address : 0x74   dac_data : 0x0
dac_address : 0x75   dac_data : 0x0
dac_address : 0x76   dac_data : 0x0
dac_address : 0x77   dac_data : 0x0
dac_address : 0x78   dac_data : 0x0
dac_address : 0x79   dac_data : 0x0
dac_address : 0x7A   dac_data : 0x0
dac_address : 0x7B   dac_data : 0x0
dac_address : 0x7C   dac_data : 0x0
dac_address : 0x7D   dac_data : 0x0
dac_address : 0x3B   dac_data : 0x1800
dac_address : 0x25   dac_data : 0x6000
dac_address : 0x3C   dac_data : 0x228
dac_address : 0x3C   dac_data : 0x28
dac_address : 0x3E   dac_data : 0x128
dac_address : 0x4C   dac_data : 0x903
dac_address : 0x4D   dac_data : 0x300
dac_address : 0x4B   dac_data : 0x801
dac_address : 0x4D   dac_data : 0x300
dac_address : 0x4E   dac_data : 0xF0F

Thank You

  • 0
    TI__Guru 66044 points

    Hi Pavan,

    The first issue at hand is the SerDes FIFO error. This means the rate coming from the Virtex 7 is not matching the 6.25Gbps that is required. I noticed the LMK setting between the low and high speed are different. In theory, the FPGA clock and SYSREF clock should remain the same, if you are using the DAC38J84 EVM. Please double check the settings as they may be incorrect. Please confirm if you are using EVM or some other PCB board that you have designed. 

    Thanks. 

  • 0 in reply to Kang Hsia
    Intellectual 670 points

    Hi

    FPGA Clk and SYSREF must be same both in High Speed and Low Speed.

    I am maintaining this, the configurations which you have addressed are DAC clocks. DACs clk are different at different Speeds.

    So now how to Resolve the SERDES FIFO ALARMS ?? 

  • 0 in reply to Pavan
    TI__Guru 66044 points

    Hi Pavan,

    SerDes FIFO alarms are due to slight rate mismatch of the SerDes input (from FPGA) and Serdes rate received at the SRX of the DAC38j84. I recommend you double check the SerDes PLL of the FPGA to ensure it is locked properly at all times. Also, please check if the FPGA and DAC devices have the reference clocks locked to a common source. If they are asynchronous (i.e. the two references are frequency locked, but not phase locked), then gradually the FPGA TX rate may drift from the DAC RX rate, and cause FIFO errors.

    -Kang

  • 0 in reply to Kang Hsia
    TI__Guru* 91947 points

    Pavan,

    Why are you writing to duplicate registers at the end of the file? I think you have the wrong settings for a few of these. Please try using the following:

    Add 0x25 data 0x6000

    Add 0x3B data 0x3800

    add 0x3C data 0x228

    add 0x3E data 0x108

    Regards,

    Jim 

  • 0 in reply to Kang Hsia
    Intellectual 670 points

    Hi Kang

    FPGA and DAC have same Clock Source (LMK04826B)

    Clocks  are length matched from LMK to  FPGA  and LMK to DAC.

    So they are Synchronous

    When I am operating only one DAC, I am not getting this isuue

    I am facing SERDES FIFO errors when I am Accessing 5 DACs 

  • 0 in reply to jim s
    Intellectual 670 points

    Hi Jim

    When I am loading Configurations from DAC38J8X GUI, I am  getting these configurations at the end.

    So I am following the same thing

  • 0 in reply to Pavan
    TI__Guru* 91947 points

    Pavan,

    I used the GUI as well and three of my settings did not match the ones you sent.

    Try the values I sent for the following addresses:

    Add 0x3B data 0x3800

    add 0x3C data 0x228

    add 0x3E data 0x108

    Regards,

    Jim

  • 0 in reply to jim s
    TI__Guru* 91947 points

    Pavan,

    So you have a board with one FPGA connected to 5 DAC's? More questions for you:

    1. Is there only one DAC that works or do all 5 work if operated individually?

    2. What happens if you only operate with 2 DAC's or 3 DAC's or 4 DAC's?

    3. Can you send your schematics?

    4. Do all 5 work when using case 1?

    5. Have you tried a sample rate between case 1 and case 2 rates?

    6. Do all 5 have the same register values in case 2? Can you do a read back to makes sure all were programmed properly?

    Regards,

    Jim