I am planning a data acquisition system with ad7175-2. I read the datasheet and I have a doubt.
Can I enable 2.5V REFOUT pin out and at same time use AVDD1-AVSS as reference source for ADC?
Yes, internal reference is output on the REFOUT pin when REF_EN bit is set. And at the same time you can change the reference source by REF_SEL bits on SETUP configuration register.
In my system the AD7176 is in continue conversion mode. So the periodic pulse on Dout pin send an interrupt signal for the microcontroller that send the read command to SPI bus and reads the data.
If I set the continue read mode on the converter, Dout remain to High level all the time. No more pulses and I can't use the MCU interrupt for read the datas. It's normal or I have missed something?
For set the converter in continue read mode, I send 3 bytes: 0x020080.
In continuous read mode, /DRDY still goes low to indicate the end of a conversion and you only need to apply the required number of SCLKs after /DRDY goes low to read a conversion. When the conversion is read, RDY returns high until the next conversion is available. The data can be read only once since the data register is updated always and the serial interface every time a conversion is ready. So, to use continuous read, the /DRDY pin needs to be closely monitored. Can you perform a reset upon power up by writing at least 64 SCLKs with DIN high to ensure that the registers are at default values. Then, device will expect to write to the communication register which is an 8 bit register only. So first send the 0x02 so that the part will interpret a write to register address 0x02, then your 0x0080 transfer to write a content to the specified register.
are you sure that datasheet of AD7176-2 is right? In my test, REFOUT is enabled when REF_EN bit si 0 and I have measured these sample frequencies codes: 0=10Khz; 1=17Khz; 2=25Khz; 3=32Khz; 7=250Khz; 8=60hz; 16=1Khz;
These codes are different as shown on pages 62 63 64 65 of the datasheet.
The datasheet is correct, when REF_EN bit is 0 or disabled there should be no output on the REFOUT pin. The corresponding ODR bits at Filter Configuration Registers (page 62-65) are also correct. May I know how did you write and read back the register contents?
Retrieving data ...