Hello everyone
I have to use ADC AD7921.
It is manageable through the SPI device. It is equipped with two analog inputs that can be selected by manipulating a MUX, through SPI.
By default, the Vin0 signal is enabled on the exit from the MUX, which I read correctly with the code I attach.
One thing I noticed is that if I decrease the freq I read incorrect values, and this thing is not clear to me since on the datasheet, p. 7, I find a Freq rage from 10 khz to 5 Mhz. What am I wrong?
Further, he goes to sample in and out on the fall.
On my uC which is a SAMD21 I selected mode 3.
The data that he sends me I receive correctly with mode 3 because, even looking at the time digram, page 7, he samples the DOUT on the falling and I on the uC I read it on the first positive front.
But instead when I send from the uC, always with mode 3, they field on the FALLING and also the ADC on the DIN samples on the FALLING. Could that be the problem?
I attach the code separately to send the channel value.
Ulteriore cosa è che guardando il diagramma temporale di pagina 8 si vede che richiede 16 colpi di clock per eseguire tutta la comunicazione; come faccio a far risultare esattamente questo numero di colpi di clock ?
Thank you
SPISettings SPI_Settings_Test_14(5000000, MSBFIRST, SPI_MODE3);
void setup() {
Serial.begin(115200);
}
void loop() {
// SPI ACTIVED
SPI.begin();
// BUS SPI ACTIVED
SPI.beginTransaction(SPI_Settings_Test_14);
// SLAVE ACTIVED
digitalWrite(FPGA_CS_VOLT_NEG, LOW);
SPI_Received_Value_BATT_480_VOLT = SPI.transfer16(0);
// SLAVE DISABLED
digitalWrite(FPGA_CS_VOLT_NEG, HIGH);
Serial.println(SPI_Received_Value_BATT_480_VOLT, BIN);
// BUS SPI DISABLED
SPI.endTransaction();
// SPI
SPI.end();
float Voltage = SPI_Received_Value_BATT_480_VOLT * (5.2/4096);
}
// SEND DATA -- CHANNEL VALUE
// ABILITO LA COMUNICAZIIONE SPI
SPI.begin();
// ABILITO IL BUS SPI
SPI.beginTransaction(SPI_Settings_Test_14);
// ATTIVO LO SLAVE
digitalWrite(FPGA_CS_VOLT_NEG, LOW);
SPI.transfer16(001000000000000); pag 17
// DISATTIVO LO SLAVE
digitalWrite(FPGA_CS_VOLT_NEG, HIGH);
SPI.endTransaction();
SPI.end();
datasheet.pdf (317 KB)