Hi Admin...
- I am interfacing ADS1158 with LPC1769(NXP).
- I want to use Fixed Channel mode & AN0 to AN14 as +input & AN15 as -input.
- Clock: 32.768Khz Crystal. CLKSEL PIN IS TIED TO GND.
- VREFP = +4.5V
- VREFN = 0
My Spi Communication is working properly as I have written some values in registers & read it back & found correct.
CONFIGURATION:
- Command= 0x70
- Config0 = 0x2A (MUXMOD = 1, STAT=1, CLKEN = 1)
- Config1 = 0x83 (Default)
- MUXSCH = 0x0F (AN0: +in AN15: -in)
- All other registers are at default value.
CODE:
- ADC1158_CS_LOW;
- str2[0] = spi_send_byte(0x30);
- str2[1] = spi_send_byte(0x00);
- str2[2] = spi_send_byte(0x00);
- str2[3] = spi_send_byte(0x00);
- ADC1158_CS_HIGH;
- for(i=1; i<4; i++)
- {
- sprintf((char*)str1,"ADD[%02uh]:0x%02x\r\n",i,str2[i]);
- UARTSend(0,str1,15);
- }
CASE 1:
- I have not connected any input at any channel. All channels are pulled low by 100k resister.
- Now As AN0 is selected I got +5.4V at AN0 pin & 0.23V at all other ANx pins of ADC. (AN0 to AN15 are pulled low by 100K)
- RESULT:
- ADD[01h]:0xdf<CR><LF>
- ADD[02h]:0x7f<CR><LF>
- ADD[03h]:0xff<CR><LF>
- <CR><LF>
- ADD[01h]:0xdf<CR><LF>
- ADD[02h]:0x7f<CR><LF>
- ADD[03h]:0xff<CR><LF>
- <CR><LF>
- ADD[01h]:0xdf<CR><LF>
- ADD[02h]:0x7f<CR><LF>
- ADD[03h]:0xff<CR><LF>
CASE 2:
- I have measured the current using (1k load) coming out from the AN0 pin is approx. 340uA. (Even if Bias Current Source is kept OFF)
- Note: Even when I configured 24uA or 1.5uA, I got same current coming out from AN0 pin is approx 340uA.
- RESULT
- ADD[01h]:0x9f<CR><LF>
- ADD[02h]:0x0a<CR><LF>
- ADD[03h]:0xf7<CR><LF>
- <CR><LF>
- ADD[01h]:0x9f<CR><LF>
- ADD[02h]:0x0a<CR><LF>
- ADD[03h]:0xfa<CR><LF>
- <CR><LF>
- ADD[01h]:0x9f<CR><LF>
- ADD[02h]:0x0a<CR><LF>
- ADD[03h]:0xfd<CR><LF>
- <CR><LF>
- ADD[01h]:0x9f<CR><LF>
- ADD[02h]:0x0a<CR><LF>
- ADD[03h]:0xfb<CR><LF>
