I have a board that uses a AY0438 and 4,7 segment displays I want to replace with a nano so I can record the data or transmit not sure on which yet. Does anyone have any idea how I should go about this.
AY0438 is an LCD driver.
Not sure what you’re trying to do… maybe start from the beginning.
I’m not sure how else to say what I’m trying todo. I want to replace a ay0438 and 4 digit 7segment display with an arduino nano to log the data and or possibly transmit it to another arduino.
That really doesn’t clarify anything…. sorry.
How about a block diagram of what you’re working with - everything… and a.couple of photos of what you’re installing.
What’s feeding the existing display?
What’s it being used for ?
I’m not trying to be rude and I know you’re trying to help but I don’t see why that’s needed. I I want to take the data that should be going to the AY0438 but have it read by an arduino instead and have it logged. The AY has 3 inputs data in , clock and latch. I need help writing code that will take those 3 and let me log it properly on an SD card and or transmit it somewhere else to be displayed.
The AY0438 apparently acts very similar to a 32bit shift register (say, 4x 74hc595 chips.) It MIGHT be readable via the SPI peripheral (in slave mode), or you can look at one of the bit-banged SPI slave implementations (or shiftin())- PROBABLY it is being driven slowly enough for an AVR to capture (can you measure the clock in the existing circuit?)
Why do not store the data BEFORE it will be transmitted to the AYo438?
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It seem to be a typical xy-problem.
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Capturing data on its way to a display is a common method for extracting data from an otherwise non-user-programmable device. I’ve seen projects where people captured and decoded the signals from a multiplex 7segment LED display.
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It’s part of a circuit I don’t want to touch. Get the display data seems like the safest way to me.
Yes I agree. @billystone90 Please read
http://xyproblem.info/
X-Y Problem
It might seem safe but it is way over the top in terms of complexity. Remember you will have a lot of decoding to do before you can get the actual information back to read, even if you can reverse engineer the masses of data you will get back.
I'd have said the project is an interesting challenge. As has been pointed out it is a 32 bit shift register where the data is readable on the falling clock edge. The 32bit block read will have a 1:1 mapping to the segments of the LCD display. The mapping will probably have to be determined experimentally unless there is also a datasheet for the display. From seeing what bits are set in the 32bit block it will be clear which digits/characters are (or would be) shown on the display. A logic analyser would be useful in this project.
What is displayed on the display, incidentally? Is it a voltage, time, temperature or what? Also interesting to know is if the display shows a static result or if it scrolls.
I think the first thing to do is find out how often the display is updated, because that will affect subsequent decisions, and even if a Nano can keep up with the data rate. It is probable that the display changes several times per second, since the human eye cannot distinguish rapidly changing digits. It might be possible to filter out unchanging data to avoid processing it downstream.
Ideally you want the data captured in the background and stored in a buffer, there are limited options to do that, SPI slave is probably the best bet. Next best thing may be pin change interrupts.
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