Reading and Writing to 1. Define a programming loop which counts from 55 to 0 and which the Shift Register contains the following.

A. Read and save the current shift register bit at the output (bit 55) position using the A/D status register (base + 0316).

B. If the loop count does not equal the bit position to be changed, write back the bit using the A/D serial register

(base + 0516). This restores the bit and shifts it to the bit 0 position, which shifts a new shift register bit to the output

(bit 55) position.

C. If the loop count does equal the bit position to be changed, write the new bit setting using the A/D serial register

(base + 0516). This sets the bit and shifts it to the bit 0 position, which shifts a new shift register bit to the output (bit 55) position.

D. Continue through the loop until the loop count is 0. This shifts each bit back to its original position.

2. After the configuration is set, write a value of 4 to the A/D parallel strobe register (base + 0B16). This copies each shift register bit to the shift register latch at which point the configuration is set.

Enabling the Inputs At power-on or following a reset, the single-ended and differential inputs of channels 1 and 2 are enabled such that input signals can be applied. An input can be disabled (and later enabled) using the following bits of the A/D shift register.

Bit

Name

 

Setting

Position

 

 

 

 

 

 

 

7

SINGEND1

0

- Ch1 S/E input disabled

 

 

1

- Ch1 S/E input enabled

 

 

 

 

12

SINGEND2

0

- Ch2 S/E input disabled

 

 

1

- Ch2 S/E input enabled

 

 

 

 

36

CH1INPT

0

- Ch1 differential input enabled

 

 

1

- Ch1 differential input disabled

 

 

 

 

44

CH2INPT

0

- Ch1 differential input enabled

 

 

1

- Ch1 differential input disabled

 

 

 

 

 

 

 

 

Procedure With the bit positions known, disable/enable the inputs as required using the procedure for reading and writing to the shift register.

Appendix C

Register Programming 369

Page 369
Image 369
HP E1429A manual Bit Name Setting