Help interfacing with a 1980's era B&O LED display

General project help for Adafruit customers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
nferrario
 
Posts: 6
Joined: Sun Apr 23, 2017 2:39 pm

Help interfacing with a 1980's era B&O LED display

Post by nferrario »

Hi,

I have a dead Bang and Olufsen Beomaster 5000 that I have scavenged for parts to repair other systems, sold most of the working components, and now it's a shell with a really cool LED display.

That shell perfectly matches the other components in my system, and I want to put a Pi in it running Volumio that I can use to stream Airplay or other sources.

The question is how do I interface Volumio with this really cool LED display. I have the schematic and all of the pinouts, but I'm not 100% sure how to interface it with Volumio. The display board is labeled HY-214, NSM4071 and connects to an Intel 8051 using a clock signal and a data signal. The schematic is attached from the repair manual and I have the pinout from it.

I'm wondering:
1. What is the standard that these communicate? Or do I need to experiment with it using an Arduino sending specific signals to find out?
2. Is there a plugin for Volumio where I can send data like this?
3. There are additional LEDs that are not controlled by an IC. If I wanted to make a graphic equalizer is there a way to wire them directly to the pi for Volumio?
IMG_6576.jpeg
IMG_6576.jpeg (106.62 KiB) Viewed 323 times
Screen Shot 2021-11-22 at 4.15.51 PM.png
Screen Shot 2021-11-22 at 4.15.51 PM.png (240.39 KiB) Viewed 323 times

User avatar
adafruit_support_bill
 
Posts: 88093
Joined: Sat Feb 07, 2009 10:11 am

Re: Help interfacing with a 1980's era B&O LED display

Post by adafruit_support_bill »

connects to an Intel 8051 using a clock signal and a data signal
It could be using i2c for communication. That protocol was developed in the early 80s at Phillips. Although I don't see any pullup resistors on the part of the schematic shown. I'd expect to see something like 4.7K resistors from the clock and signal line somewhere on the bus.

In any case, reverse engineering the data sent would be easier to do if you could 'sniff' the lines while in actual operation.

User avatar
nferrario
 
Posts: 6
Joined: Sun Apr 23, 2017 2:39 pm

Re: Help interfacing with a 1980's era B&O LED display

Post by nferrario »

Thanks - I think I can attach it to another amp in operation to test if need be.

I also discovered the HY214A94V0 is the display part number, but the controller on the board is a mystery. All the service manuals list the part number interfacing with a controller over 2 wires (clock, data) which I assume is SPI but can find no additional documentation on the standard.

Can I assume starting with 9600 as the clock standard or does it vary wildly? I'll probably connect the display to an Arduino with a 1k resistor on clock and data per the schematic, then start sending bits to test the output.

User avatar
adafruit_support_bill
 
Posts: 88093
Joined: Sat Feb 07, 2009 10:11 am

Re: Help interfacing with a 1980's era B&O LED display

Post by adafruit_support_bill »

There is no formal standard for SPI. The most common variants use 4 wires: MOSI, MISO, SCK and CS. But for 'write only' devices you can omit the MISO. And with only one device on the bus you can also just tie CS permanently low.

As for clock speed, there is no SPI standard either. 'Standard' speed for I2C is 100KHz - but it can be changed. Most Arduino boards default to 4MHz for SPI and 100KHz for I2C. In both cases, it is controlled by the Master and the slave should respond up to its own maximum speed capability.

If you have another amp to drive it with, you should be able to put a scope on the clock line and see what is used. If you are using an Arduino to drive it, you can start slow and increase the speed until you find the max reliable operating frequency.

Locked
Please be positive and constructive with your questions and comments.

Return to “General Project help”