Hello I am having some issues with what I am seeing as output on the ADS1298 and believe it has to do with the configuration of the registers. To help debug this I am trying to get RLD_OUT to be measured on various channels. I have outlined the schematic/channel config below along with my Register Configuration. I have been trying to measure the RLD to help Debug this in which I am not even seeing anything on the RLDOUT pin when I configure the Device to use the internal Ref for RLD and Enable the Buffer.
Shouldn't I see a voltage output of (AVDD-AVSS)/2 on the RLDOUT pin when this is configured?
Do the RLD_SENSP/N setting dictate whether this occurs?
I should still see this even if I am in Test Mode correct?
Sch/Channel Setup:
Ch1 = V1 = V1-WCT
Ch2(LL connected to IN2P RA connected to IN2N): LEAD I = LA - RA
Ch2(LL connected to IN2P RA connected to IN2N): LEAD II = LL - RA
Ch3 = V6 = V6 - WCT
Ch4 = V5 = V5 -WCT
Ch5 = V4 = V4 - WCT
Ch6 = V3 = V3 - WCT
Ch7 = V2 = V2 - WCT
Ch8 = V1 = V1 - WCT
We are running this in WCT_TO_RLD mode which I am not convinced is configured correctly on the schematic. As the datasheet indicates RLD_OUT should be shorted to RLD_INV and they have a RC filter with 390K and .01uF between RLD_OUT and RLD_INV?
CONFIG REG SETTINGS:
/* Set the config Registers (this is the first chunk). */
//CONFIG1: High Res Mode, 1kHz Data_Rate: HR_1K_SPS is already OR'd with CONFIG_1_HIGH_RES
config_data[0x00] = (ADS129X_CONFIG_1_HR_1K_SPS);
//CONFIG2: Constant Chop Freq, TEST_AMP=1(2x -(VREFP-VREFN)/2400 V
config_data[0x01] = (ADS129X_CONFIG_2_WCT_CHOP_CONST | ADS129X_CONFIG_2_INT_TEST_EN |
ADS129X_CONFIG_2_TEST_AMP_2X | ADS129X_CONFIG_2_TEST_FREQ_2HZ);
// CONFIG3: Since External VREF is being used Disable Internal VREF Buffer, VREF=External
// RLDREF=Internal, PD_RLD(ON), RLD_LOFF_SENS=?, RLD_STAT = ?
config_data[0x02] = ((1 << 6) ADS129X_CONFIG_3_RLD_MEAS_MUX |ADS129X_CONFIG_3_RLD_REF_INT |
ADS129X_CONFIG_3_RLD_POWER_EN );
config_data[0x03] = (ADS129X_LOFF_FLEAD_OFF_DC); // LOFF
//Set all channels to PGA GAIN = 6, Configure Ch3 & Ch6 To measure RLD
config_data[0x04] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_TEST); // CH1SET=LEAD1 = LA-RA
config_data[0x05] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_TEST); // CH2SET=LEAD2 = LL-RA
config_data[0x06] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_RLD_MEAS); // CH3SET=V6 = V6-WCT
config_data[0x07] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_TEST); // CH4SET=V5 = V5-WCT
config_data[0x08] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_TEST); // CH5SET=V4 = V4-WCT
config_data[0x09] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_RLD_MEAS); // CH6SET=V3 = V3-WCT
config_data[0x0A] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_NORMAL); // CH7SET=V2 = V2-WCT
config_data[0x0B] = (ADS129X_CHxSET_GAIN_6 | ADS129X_CHxSET_MUX_NORMAL); // CH8SET=V1 = V1-WCT
//RLD_SENSEP => How does this tie into measuring RLD? Using WCT_TO_RLD...
config_data[0x0C] = (0x06); // RLD_SENSP
//RLD_SENSEN => Same question as RLD_SENSEP, WCT is connected to IN3N,IN4N,IN5N,IN6N,IN7N,IN8N
config_data[0x0D] = (0x06); // RLD_SENSN
// LOFF_SENSP
config_data[0x0E] = (0x00); // LOFF_SENSP
// LOFF_SENSN
config_data[0x0F] = (0x00); // LOFF_SENSN
// LOFF_FLIP
config_data[0x10] = (0x00); // LOFF_FLIP
Ads129xRegWrite_sync(info, ADS129X_CONFIG_1, config_data, 0x11);
//Need to split up Config Register writes as LOFF_STATP and LOFF_STATN are Read-Only Registers
config_data[0x00] = (0x01); // GPIO
config_data[0x01] = (0x00); // PACE
config_data[0x02] = (1 << 5 ); // RESP
//CONFIG 4: Continuous Mode(default), WCT_TO_RLD: ON/OFF?,
config_data[0x03] = (ADS129X_CONFIG_4_LOFF_COMP_ON | ADS129X_CONFIG_4_WCT_TO_RLD_ON ); // CONFIG4
// WCT1: WCTA is connected to RA electrode, RA is connected to IN2N/IN1N on schematic.
config_data[0x04] = (ADS129X_WCT1_WCTA_POWER_ON | ADS129X_WCT1_WCT_AMP_A_CH1_N ); // WCT1
// WCT2: WCTB is connected to LA, Schematic LA = IN1P
// WCT2: WCTC is connected to LL, Schematic LL = IN2P
config_data[0x05] = (ADS129X_WCT2_WCTB_POWER_ON | ADS129X_WCT2_WCT_AMP_B_CH1_P | // WCT2
ADS129X_WCT2_WCTC_POWER_ON | ADS129X_WCT2_WCT_AMP_C_CH2_P);
Ads129xRegWrite_sync(info, ADS129X_GPIO, config_data, 0x06);
I have tried to include a schematic of the ADS1298 but not sure if it is getting attached correctly?
3146.NAD01-80001-03-SCH, Short.pdf
Regards,
Frank