Category: Hardware
Product Number: MAX1258
Hi, I have an issue using a MAX1258.
Here is my situation :
Using Internal Vref = 4,096V
Configured registers :
static uint8_t reg_setup_buff[1] = {0b01110000}; // Reserved = 01 CKSEL = 11, REFSEL=00, DIFSEL=00
static uint8_t reg_adc_buff[1] = {0b00110001}; // Reserved = 001, AVGON=1, NAVG=00, NSCAN=01
static uint8_t reg_conversion_buff[1] = {0b10000110}; // Reserved = 1, CH=XXXX, SCAN =11, TEMPERATURE=0
With a voltage of 1V applied to AIN0, the adc answers 0x0300 = 768
With a voltage of 1.5V applied to AIN0, the adc answers 0x0400 = 1024
With a voltage of 2V applied to AIN0, the adc answers 0x0700 = 1792
With a voltage of 2.5V applied to AIN0, the adc answers 0x0800 = 2048
With a voltage of 3V applied to AIN0, the adc answers 0x0A00 = 2560
Since the ref internal ref is 4.096V, 1bit = 0.001V
So I suspect that the ADC isn't sending the LSB of the result.
as 1V sould be : 0x03E8 = 1000
as 1.5V sould be : 0x05DC = 1500
as 2V sould be : 0x07D0 = 2000 etc...
Here is my SPI config of my MCU (ST SPC58):
Here is some resuls from my logic analyser for a measure with 1V on AIN0 :
Thanks a lot in advance for your help.
Best regards,
Julien
