Hello Bob,
Hello Mr.BOB, I am sending as attachment i.e. (Please visit the site to view this file)my schematic of ADS1148 for 32 channel universal input DAS. Following are the details of the circuit and some query related to it:
1) Ports P0.2, P0.3, P0.4, P3.0, P3.1 and P3.2 re the SPI interface ports to my microcontroller. All these lines are connected to SPI interface ports of ADS1148 for 32 channel input. I wanted to know whether it is OK to connect all these lines including DRDY, START and RESETlines of 8 ADS1148 (8 x 4 = 32channel) and give it to the microcontroller.
2) Referring the EVM board, I have connected BAT54 between AVss and AGND and also between REFP0 and AVdd. Also 5.1V Zener connected to REFP0.
3) Resistors R11 to R14 and C20 to C25 are for filtering the inputs along with torroidal.
4) SW1 is to select input for 4-20mA.
5) I have given 2.5V zener to REFP1.
6) Also Capacitors C15 to C17 = 10UF(non polarized) were added after referring the EVM.
7) For filtering of reference (REFP0, REFP1) resistors R21, R22, C26, C27 and C28 are after referring application report SBAA201.
8) Resistance R23 is Rbias for RTD input.
9) Power supply section , U7 and J10 is part of my circuit which would change depending on my application . At present it just gives the required 3.4V or 5V required for the ADS1148 circuit.
Please check whether the circuit is OK or whether some modifications are required since we are making our 1st prototype using ADS1148.