AFE 4490 Register values are not set

Hello Santosh,

In the failing boards, could you monitor the supply voltages, TX_REF pin, BG pin, VCM pin and CLKOUT pin?
Also what values do you read on the DIAG_REG?

We are getting TX_REF = 1.0v, BG = 1.0v, VCM =0.9v and CLKOUT = 3.968 MHz signal.
We are getting DIAG_REG 0x001930 or 0x001EE0 when probe is connected and 0x001920 when probe is not connected
In some boards TXM and TXP is showing 5.0v for all settings ( 0.5v /0 .75v / 1.0v)

Hi,
Please tell me how to read Values of LEDCNTRL REG and CONTROL1,CONTROL2 REG

Regards
Santosh Pawar

Hi

We are getting TX_REF voltage 3.0v and 5.0 v  in some boards.

We have also observed that only control2 reg is not setting properly(ie. bits TX_REF, TX_power down).

Other bits RST_CLK_ON_PD_ALM,EN_ADC_BYP,TXBRGMOD sete/resets properly.

Regards,

Santosh pawar

HI,

Please Reply ASAP for above issue

Regards,

Santosh pawar

Santosh,

1. Could you please send us a copy of your schematics?

2. Could you also send us your default register settings and is each board loaded with these defaults?

3. What do you mean by you "observed that only control2 reg is not setting properly"? Does this mean you tried to set these bits and read back the register or did you verify by measuring the voltages?

Hi,

Please find Schematic  and setting file attached herewith.

 CONTROL2  REG settings like TX_REF voltage is not setting properly.

CONTROL1 REG is updated as per Settings.

#define SAMPLE_256

#ifdef SAMPLE_256

#define AFE4490_CONTROL0 0x00000004
#define AFE4490_LED2STC 0x01002DC6
#define AFE4490_LED2ENDC 0x02003D06
#define AFE4490_LED2LEDSTC 0x03002DC6
#define AFE4490_LED2LEDENDC 0x04003D07
#define AFE4490_ALED2STC 0x05000000
#define AFE4490_ALED2ENDC 0x06000F40
#define AFE4490_LED1STC 0x07000F42
#define AFE4490_LED1ENDC 0x08001E82
#define AFE4490_LED1LEDSTC 0x09000F42
#define AFE4490_LED1LEDENDC 0x0A001E83
#define AFE4490_ALED1STC 0x0B001E84
#define AFE4490_ALED1ENDC 0x0C002DC4
#define AFE4490_LED2CONVST 0x0D000002
#define AFE4490_LED2CONVEND 0x0E000F41
#define AFE4490_ALED2CONVST 0x0F000F44
#define AFE4490_ALED2CONVEND 0x10001E83
#define AFE4490_LED1CONVST 0x11001E86
#define AFE4490_LED1CONVEND 0x12002DC5
#define AFE4490_ALED1CONVST 0x13002DC8
#define AFE4490_ALED1CONVEND 0x14003D07
#define AFE4490_ADCRSTCT0 0x15000000
#define AFE4490_ADCRENDCT0 0x16000000
#define AFE4490_ADCRSTCT1 0x17000F42
#define AFE4490_ADCRENDCT1 0x18000F42
#define AFE4490_ADCRSTCT2 0x19001E84
#define AFE4490_ADCRENDCT2 0x1A001E84
#define AFE4490_ADCRSTCT3 0x1B002DC6
#define AFE4490_ADCRENDCT3 0x1C002DC6
#define AFE4490_PRPCOUNT 0x1D003D08
#define AFE4490_CONTROL1 0x1E000101
#define AFE4490_SPARE1 0x1F000000
#define AFE4490_TIAGAIN 0x20000000 //0x20000000
#define AFE4490_TIA_AMB_GAIN 0x21000000
#define AFE4490_LEDCNTRL 0x22017F7F //2828 //0x22011414
#define AFE4490_CONTROL2 0x23020000 //0x23000000 // TX is kept for 4.75-5.25 V supply //0x23020000 // TX is kept for 3 V supply
#define AFE4490_SPARE2 0x24000000
#define AFE4490_SPARE3 0x25000000
#define AFE4490_SPARE4 0x26000000
#define AFE4490_SPARE5 0x27000000
#define AFE4490_SPARE6 0x28000000
#define AFE4490_ALARM 0x29000000
#define AFE4490_LED2VAL 0x2A000000
#define AFE4490_ALED2VAL 0x2B000000
#define AFE4490_LED1VAL 0x2C000000
#define AFE4490_ALED1VAL 0x2D000000
#define AFE4490_LED2-ALED2VAL 0x2E000000
#define AFE4490_LED1-ALED1VAL 0x2F000000
#define AFE4490_DIAGNOSTICS 0x30000000

#endif

spo2_CIRCUIT.pdf

Santosh,

In your schematic I see that you left TX_REF pin (pin 9) floating. This should have a 2.2uF decoupling capacitor on it. I am checking with our systems team in India if this would cause your issue, but it is something that you should fix.

One other question: How do you know TX_REF is not set properly? Are you writing to CONTROL2 register and reading the wrong value when you read back? OR Are you writing to CONTROL2 register and measuring the TX_REF voltage at the pin?

Hi Amy,

We have Checked CONTROL2 REG setting by measuring TX_REF voltge at pin.

Thanks and Regards,

Santosh pawar 

HI,

In some boards we are also getting some noise pulses on RX_DIG_SUPPLY pin no 31(see attached image).

That board was working properly earlier but  when we tried to read register settings it stops working and now it is showing TX_REF voltage 2 volts.

Timing of these pulses varies  with PRP_COUNT.

We also connect decoupling capacitor 2.2uF as per your suggestion but it is showing same problem.

Thanks and Regards,

Santosh pawar 

HI,

In some boards we are also getting some noise pulses on RX_DIG_SUPPLY pin no 31(see attached image).

That board was working properly earlier but  when we tried to read register settings it stops working and now it is showing TX_REF voltage 2 volts.

Timing of these pulses varies  with PRP_COUNT.

We also connect decoupling capacitor 2.2uF as per your suggestion but it is showing same problem.

Thanks and Regards,

Santosh pawar 

HI,

In some boards we are also getting some noise pulses on RX_DIG_SUPPLY pin no 31(see attached image).

That board was working properly earlier but  when we tried to read register settings it stops working and now it is showing TX_REF voltage 2 volts.

Timing of these pulses varies  with PRP_COUNT.

We also connect decoupling capacitor 2.2uF as per your suggestion but it is showing same problem.

Thanks and Regards,

Santosh pawar 

Santosh,
For these experiments, are you separating the TX and RX supplies? What kind of power supply are you using for each of these?

Hi  Amy,

We are using separate TX and RX supply. We are using Linear regulator supply.

Thanks and Regards,

Santosh pawar