MCP2221 I
2
C Demonstration Board User’s Guide
DS50002480A-page 32
2016 Microchip Technology Inc.
Figure 3-10
shows how to configure the DAC to output 1.45V.
FIGURE 3-10:
CONFIGURING THE DIGITAL-TO-ANALOG CONVERTER
3.3.7
Digital I/O Pins Tab
The MCP23008 pin expander provides access to eight configurable digital input/output
pins. Short-circuiting jumper J20 connects LEDs, LD2, LD3,…,LD9, to the eight pins.
The eight general purpose pins are also accessible via connectors J16 and J17. For
example, if a pin is configured as an output and intended to be connected to an external
circuit or component via J16 or J17, it may help to remove jumper J20 in order to
preserve the pin’s current driving strength.
In case a pin is used as a digital input, a logical high input signal should match the
demonstration board’s power level (3.3V or 5V, determined via jumper J19). For more
information on voltage tolerances, see the
“MCP23008/MCP23S08 Data Sheet”
(DS21919).
Even when switching to a different application tab (such as for measuring resistors), if
the pin state monitoring (auto-read) is enabled, then it will not be automatically halted
unless the board is physically disconnected from the PC. Therefore, it is recommended
to stop performing the readings when they are no longer required.
Custom LED notifications for pin GP0 (for example: the pin having a logical high state
results in a yellow LED blinking on the board) are described in
Section 3.3.8 “RGB
LED Notifications Tab”
.
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