Rabbit OP7100 User Manual download pdf (Page 28)

22 eDisplay (OP7200)

3.3.2 Digital Outputs

The OP7200 has eight digital outputs, OUT0–OUT7, which are individually configurable

with the digoutConfig or digoutTriStateConfig software function calls as sinking

(up to 350 mA per channel) or as sourcing (up to 250 mA per channel). Figure 9 shows a

wiring diagram for using the digital outputs in a sinking or a souring configuration.

Figure 9. OP7200 Digital Outputs

All the digital outputs are in the high-impedance tristate when the OP7200 is initially

powered on or reset. The CPLD (U4) then enables either the sink control or the source

control to operate the digital outputs as sinking or sourcing, and thereby serves as a hard-

ware block to prevent both sinking and sourcing drivers from being activated at the same

time in a given channel.

Although the components are not installed, there is provision on the circuit board for the dig-

ital outputs to be pulled as a group to Vcc, +K, or to GND through 27 kΩ resistors. In spe-

cial circumstances, you may need to pull sinking outputs high to either Vcc or +K, or you

may need to pull sourcing outputs to GND, for example, when driving low-level logic sig-

nals. Pulling the digital outputs up to +K allows the current-sinking outputs to be used as

voltage outputs where their upper level is controlled by the voltage of +K. OP7200 series

SINKING OUTPUTS

SOURCING OUTPUTS

Current

Flow

Current

Flow

CPLD

SINK

CONTROL

SIGNAL

CPLD

SOURCE

CONTROL

SIGNAL

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Rabbit OP7100 User Manual Page 28