Hi, so I wanted to know if there was any way to intercept the information being processed and measured by separate electronic devices. Like, say a thermometer or a blood pressure machine. They use various sensors and finally compute the needed data to display the output. Is there a way to obtain this output from the machine for further processing within the Raspberry Pi? Maybe intercepting the information on its way to the LCD screen? Anyway to convert it to readable data?
Intercepting information from various electronic devices into a raspberry Pi
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Fadel -
May 30, 2023 at 3:42 PM -
Thread is Unresolved
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SkyeFire
May 30, 2023 at 3:48 PM Approved the thread. -
Depends entirely on the nature of the sensor, and where you intercept the data. Also, many commercial devices deliberately make this as difficult as possible in order to prevent people from tinkering with their product.
For example, some temperature sensors output analog voltages, but others may output digital values, and those may use I2C, or SPI, or some proprietary protocol. The analog-output sensors may output a "usable" voltage between 0V and 3.3V, or 5V, or 10V, but others may only output microvolts that need to be passed through a special amplifier to get up into a typical usable range. And intercepting the low-voltage side might well distort the readings, unless you really know what you're doing with low-V high-impedance electronic design.
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is there anyway that i can intercept the data to the lcd display consistently, as they all work on the same principle?
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if you know the used principle you can take advantage of anything.
few problems that i see:
LCD displays are not all equal. some products use module based on some LCD controller (like HD44780) , while others are directly driven.
display versions that use own LCD controller are easier to manage - far fewer signals and usually signal connections are also MUCH easier to access. interface can be parallel, SPI, I2C, serial etc.
directly driven LCDs are more challenging since they are multiplexed, terminations are tiny and there is LOTS of them. if you ever opened calculator, clock etc you would likely see zebra strips. connecting so many connections to an IO, capturing always changing levels (AC coupled) data and figuring out how it was multiplexed is not the simplest task.
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is there anyway that i can intercept the data to the lcd display consistently, as they all work on the same principle?
If you pick one model of LCD and stick to it, yes. As Panic says, LCD displays come in a wide variety of sizes, shapes, and types. Some models have software libraries for microcontrollers or Pis that would simplify your programming workload, but generally each library is limited to a single LCD product, or a single family of LCDs.