NCV7750GEVB
3
Using the NCV7750GEVB
The first thing the user must do is ensure that all jumpers
are connected. Also ensure that all DIP switches and the
continuous toggle switch are all in the downwards position.
After this is confirmed, the user can connect a ~14 V supply
to VBAT banana input and a ground connection to the GND
banana input. After this, the board will power on and a splash
screen will appear.
Figure 2.
After three seconds, this display will clear and the input
and output screen will appear.
Figure 3.
At this point we can explain the user interface. The top line
displays the current status of the NCV7750. The second line
shows column headers, where C1, C2
…
stand for Channel
1, Channel 2, etc. The third and fourth lines show the least
significant eight bits of the input and output from SPI
transmission. The most significant eight bits are unused by
the NCV7750, and are thus not displayed.
The possible statuses/modes that the chip may be in are
listed below:
•
Disabled – EN is set to low. The NCV7750 will not
respond to SPI transmission, but may enter Limp Home
state
•
Ready – The NCV7750 is able to accept a new SPI
transmission. In this state, the current output is
maintained until the transmit button is pressed
•
Continuous – The NCV7750 is continuously accepting
SPI transmission. Thus, a change in the DIP switches
for Channels 1
−
4 is immediately realized on the outputs
•
Demo – The NCV7750 is accepting a pre
−
coded
sequence of SPI transmissions. User input is disabled
for the duration of the demo. The demo is accessed by
pushing the transmit button while in continuous mode
(Continuous Transmission switch up), and it drives the
LEDs to light up in a pattern
•
Demo ending – The demo will finish after the current
sequence loop finishes
•
Demo over – The demo has completed and the user
may release the transmission button
•
Limp Home – The NCV7750 is in LHI (Limp Home)
mode. The display will reflect this by displaying Xs
over the input, as SPI input is disabled in this state.
User control is instead accepted from the IN1
−
IN4
switches. When SPI input is sent, it will not update the
outputs, but SPI output will be received as normal to
diagnose faults
•
Done – SPI transmission is complete and the user may
release the transmit button
Demo Mode
While in continuous mode (Continuous Transmission
switch up), the user can press the transmit button to enter
demo mode. In demo mode, a pre
−
programmed sequence of
SPI inputs is sent to the NCV7750. It lasts for roughly 6
seconds, and will loop. In order to stop the looping, hold the
transmit button again until “Demo ending” appears as the
status. After it is complete, the NCV7750 will return to
either Continuous or Ready state, depending on if the
continuous switch was switched off during the demo. If the
user has not yet released the transmit button, a “Demo over”
status will show.
