Hello,
I am barley new to working with these products.
So I bought one 7-Segment Display and the Large Digit Driver.
Soldering the two components was no problem.
Now I want to connect and use the display with my raspberry pi 3.
Is there a manual or any further informations on how to connect the large digit driver to the raspberry pi’s gpio?
Kind Regards,
Chris
The Raspberry Pi has 3.3V GPIO. The shift register on the Large Digit Driver is a 5V device. The datasheet (https://cdn.sparkfun.com/datasheets/Wid … C596.pdf) says the minimum voltage for a logic high should be 0.85*Vcc, which is 4.25V. You may have trouble using the LDD with a RPi unless you put a logic level converter in between.
As far as I know the the Raspberry Pi 3 hast also a +5V GPIO pin. So this should work?
The Large Digit Driver Hookup Guide shows this input Pin Description:
GND Connect to ground
LAT Data transfer in from SER on the rising edge of the latch pin
CLK Data transfer in from SER on the rising edge of the clock pin
SER Serial data in
5V Connect to power (5V)
12V Connect to power (12V)
I need to know on which Raspberry Pi GPIO pins I can connect LAT, CLK, SER?
Best Regards,
Raspberry Pi has no 5V GPIO.
You can connect the latch, clock, and serial data pins to any of the (level-shifted) GPIO. Just make sure the program you use to drive it is configured to use the pins that you’ve chosen. There is a hookup guide at https://learn.sparkfun.com/tutorials/la … okup-guide that shows how to use it with an Arduino. It has example code that can be adapted.
I think he’s confused about the +5V pin vs GPIO voltage levels.
lyndon:
I think he’s confused about the +5V pin vs GPIO voltage levels.
Actually I am a confused… I will try this:
get an external 12v power supply for the 12 v pin since raspberry has no vin pin
connect the 5v pin to the raspberry pi 5v
latch, clock, and serial data pins to any of the (level-shifted) GPIO
Adafruit just released a new RPi GPIO expander that also does 5V logic levels by default. It’s only $10. It would probably work well for your project. https://learn.adafruit.com/gpio-expande … t?view=all
how can I connect an external 12v power supply to the large digit driver?
The power supply has two wires but the large digit driver only one 12v connector.
Can I connect the other wire to the large digit driver gnd?
For what it’s worth, I just tried the Large Digit Driver with a 3.3 volt Arduino and the shift register seems to be fine with a 3.3 volt supply and I/O so you’re probably OK to use these on a Pi. Just connect the Large Digit Drivers 5V pin to 3.3 volts and your 3.3 volt I/O will likely be fine. The diagram below shows how to connect things.
It’s good to know that it works at 3.3V. However, section 8.4.1 of the datasheet for the shift register says
This device works normally during 4.5 V ≤ V(VIN) ≤ 5.5 V, when operation voltage is lower than 4.5 V. The behavior of device can’t be ensured, including communication interface and current capability.
This, to me, indicates that you would not want to operate it at less than 4.5V for anything mission critical and that performance may vary from device to device.
