2.7.2 A/D Conversion Trigger Modes
A-812PG supports three trigger modes.
1 : Software Trigger :
Writing any value to A/D software trigger control register, BASE+A, will initiate an
A/D conversion cycle. This mode is very simple but very difficult to control sampling
rate.
2 : Pacer Trigger Mode :
The pacer timer can give very precise sampling rate.
3 : External Trigger Mode :
When a rising edge of external trigger signal is applied, an A/D conversion will be
performed. The external trigger source comes from pin 1 of CN3.
2.7.3 A/D Transfer Modes
A-812PG supports three transfer modes.
1 : Polling transfer :
This mode can be used with all trigger modes. 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. The user can set the IRQ
level by adjusting JP5. A hardware interrupt signal is sent to the PC when an A/D
conversion is completed.
3 : DMA transfer :
This mode can be used with pacer trigger or external trigger. The user can set the DMA
channel by adjusting JP6 and JP7. The hardware DMA request will send signals
sequentially to the PC when an A/D conversion is completed. The single mode transfer
of 8237 is suggested.
If using interrupt or DMA transfer, it is recommended to use A-812PG software
driver.
A-812PG Hardware Manual (Ver.1.2, Sep/2005, IPH-004-12) -----
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