4-6 IC697VAL348 8-Channel, 16-bit Digital-to-Analog Converter Board User’s Manual GFK-2059
– December 2001
4
VMEbus Interface Description The VMEbus interface (Figure 4-4 on page 4-9) contains the necessary logic to interface a DAC
board to the VMEbus. The DAC is memory mapped in the VMEbus short I/O address space.
During a Write cycle to the board, address bits A05 through A15 are compared with the previously
selected board address. DIP switches select the board address. If the address compares, then a
board select signal is issued. This signal along with the control signals received at the board, gate
the data (D0 to D15) to a selected DAC or the CSR on the DAC. Address bits A01 through A03
select one of the eight DAC channels. Data D0 through D15 is latched into the selected DAC
Register. Address bit A04 is used to select the CSR.
The DAC circuitry requires +5 V, +15 V, and -15 V, the +5 V is supplied to the board via the P1
and P2 connectors. An on-board DC-to-DC converter generates the +15 V and -15 V for the analog
circuitry (refer to Figure 4-5 on page 4-11). Thus, the DAC board only needs +5 V from the chassis
power supply.