Interfaces and Connectors
EBX-18 Hardware Reference manual
41
DMA Controller
The DMA circuitry incorporates the functionality of two 82C37 DMA controllers with seven
independently programmable channels. The Master DMA Controller (DMA-1) corresponds to
DMA Channels 0-3 that are hardwired to 8-bit count-by-byte transfers and the Slave DMA
Controller (DMA-2) corresponds to Channels 5-7 that are hardwired to 16-bit count-by-word
“address shifted” transfers. DMA Channel 4 is used to cascade the two controllers and will
default to cascade mode as it cannot be used for any other purpose. In addition to accepting
requests from DMA slaves, the DMA controller also responds to requests that are initiated by
software.
The Vortex86DX2 provides the timing control and data size translation for the DMA transfer
between memory (ISA or DRAM) and the ISA Bus I/O. Also, the DX2 is ISA-compatible with
24-bit addressing. For information on programming the DMA controller, contact
Vortex86DX2 SoC On-chip Temperature Sensor
Contact the factory for information on reading and writing to the thermometer circuits.
Watchdog Timers
The watchdog timers use the RTC frequency (32.768 kHz) for a 24-bit counter, providing a time
range from 30.5
μs to 512 seconds with a resolution of 30.5 μs. When the timer is enabled and
its count reaches the programmed value, a system reset, NMI, or IRQ may occur as selected
using the Watchdog Configuration sub-menu in the BIOS Setup program.
Industrial I/O Functions and SPI Interface
The EBX-18 employs a set of I/O registers for controlling on-board analog input, digital I/O, and
external serial peripheral interface (SPI) devices. These functions share control and data
registers located at I/O addresses whose range depends on programmed FPGA PCI BAR added to
offsets 0x00-0xFF. Refer to the
EBX-18 Programmer’s Reference Manual
(available on the
EBX-18 Product Support Web Page
) for additional information.