Omega Engineering OME-A8111 3 A/D Transfer Modes, Using software trigger and polling transfer

2.7.3A/D Transfer Modes

OME-A-8111 supports two transfer modes.

1 : polling transfer :

This mode can be used with all trigger modes. Detailed information is given in section 2.4.8.The software scans A/D high byte data register, BASE+5, until READY_BIT=0.The low byte data is also ready in BASE+4.

2 : interrupt transfer :

This mode can be used with pacer trigger or external trigger. Detailed information is given in section 2.4.8.The user can set the IRQ level by register mode. A hardware interrupt signal is sent to the PC when an A/D conversion is completed.

2.7.4Using software trigger and polling transfer

If the user needs to directly control the A/D converter without the OME-A-8111 software driver, it is recommended to use software trigger and polling transfer. The program steps are listed as below:

1.Send 0x01 to A/D mode control register (software trigger + polling transfer)

(refer to sec. 2.4.8).

2.Send channel number to multiplexer control register (refer to sec. 2.4.7).

3.Send the gain control code value to gain control register (refer to sec. 2.4.6).

4.Delay the settling time (refer to sec. 2.4.6 and sec. 2.4.6).

5.Send any value to the software trigger control register in order to generate a software rigger signal (refer to sec. 2.4.9).

6.Scan the READY bit of the A/D high byte data until READY=0 (refer to sec. 2.4.2).

7.Read the 12 bits of A/D data (refer to sec. 2.4.2).

8.Convert these 12 bits of binary data to floating point value

(refer to OME-A-8111 DOS Software Manual, sec. 4.7 and sec. 4.8)

OME-A-8111 Hardware Manual (ver.1.1, Jul/2003) 23