VOGONS


First post, by Hamby

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Pardon my ignorance, but I don't know much about Raspberry Pi or the other SBCs. However, I keep hearing people talking to them via their "gpio" pins. I've read where it's used for everything from communicating with CNC machinery, talking to data collection devices, even driving an LCD display.

I was wondering if there's any kind of ISA or PCI interface card to GPIO? On the one hand for communicating with a raspberry pi from a vintage PC, or doing the other things I listed above? The idea of driving an LCD or LED display from one of my vintage PCs particularly interests me (such as a case display for CPU speed/temp/personal message).

Reply 1 of 11, by wiretap

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No, but you could accomplish the task a lot easier in different ways. There are various 5.25" bay and 3.5" bay LCD/VFD modules that work with both serial and USB you could use. If you're dead set on using a Raspberry Pi, you could just hook it up via serial and have the retro PC send the data messages across the serial link to the Pi, which would then display the data on a screen however you see fit.

edit: I mis-read.. yes, there are both ISA and PCI cards that offer GPIO, but see above, since you don't need it and can just use serial communication. The motherboard of your retro PC likely has it. Additionally, it would be easier to have the Pi to use its GPIO for other control functions if you wanted to program more than just a display. (relay output controls, sensor inputs, etc)

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Reply 3 of 11, by Tiido

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LPT port offers a whole lot of user controllable IO for comms with external world. Main problem is getting 5V safe for 3.3V devices.

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Reply 4 of 11, by 133MHz

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GPIO stands for General Purpose Input Output, it's not a protocol or a standard like say HDMI or SATA that is meant for interoperability and has a clear purpose. GPIO is pretty much the opposite - it usually refers to one or more digital I/O lines which don't have any fixed purpose and are directly under user control, there's no unified "GPIO port" for peripherals to plug into, depending on the platform and device it can mean totally different things. In the PC realm there are expansion cards which add a bunch of external I/O like the IO-48 and IO-56 that can be considered a form of GPIO, and which the latter was typically used to dump video game ROM cartridges. Said cards aren't common at all but for hobbyist use the good 'ol parallel (printer) port made for a nice GPIO solution for interfacing to all sorts of cool things, providing a decent number of I/O lines, being easy to program and being included with most PCs solidified its popularity among us tinkerer-types.

If you like retro PCs and Arduino-like peripherals then a parallel port and a cut-up printer cable should be right up your alley. 😀

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Reply 5 of 11, by elod

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Hamby wrote:

Pardon my ignorance, but I don't know much about Raspberry Pi or the other SBCs. However, I keep hearing people talking to them via their "gpio" pins. I've read where it's used for everything from communicating with CNC machinery, talking to data collection devices, even driving an LCD display.

If you to control simple things (transistors, reading digital contacts) then yes, you can do that from the PC.
The moment you need something more like an LCD (needs some serious driver logic) you're better off in the Arduino/Raspberry world. Why? Simply because that's where development is happening right now so you have a huge software library and tutorials for basically anything you'd want. You build Lego style.
Unfortunately life is too short to always reinvent the wheel so unless you are seriously interested in the exact details of these devices you're better off being an ignorant who can interface them.

Reply 6 of 11, by stamasd

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There are many LCD and OLED displays these days that dave a serial interface built-in. All you need to control them are 2 signals: data and clock. A parallel port could control 4 of these if not more (by repurposing control lines as well) with an appropriate driver.

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Reply 7 of 11, by Hamby

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There are many LCD and OLED displays these days that dave a serial interface built-in. All you need to control them are 2 signals: data and clock. A parallel port could control 4 of these if not more (by repurposing control lines as well) with an appropriate driver.

What about a midi/gameport? Could it be repurposed for the same thing? I've got a multi-io card with pinouts for a gameport that I won't need since I have a soundblaster.

(hm... just dug in the closet and found a parallel card I could use...)

Reply 8 of 11, by Tiido

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MIDI will give you a 5V level UART to toy with, remaining stuff in GamePort is read only from computer's perspective, you can get data but not send anything.

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Reply 10 of 11, by gdjacobs

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If a parport setup isn't sufficient, I'd recommend an Arduino (or other micro) to convert from your PC to whatever.

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Reply 11 of 11, by Jo22

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Arduinos (or Genuinos) are interesting, I think, because they can be built from scratch.
All it needs (for an Uno) is the Arduino boot-loader and an Atmel ATmega328P or compatible micro controller chip.

Edit:

Hamby wrote:

What about a midi/gameport? Could it be repurposed for the same thing?

The gameport (without MIDI) is nice for reading data, especially as an ADC. It has four analogue and digital inputs. It can also provide an "output", if you wish.
Things like LCDs where often connected to the LPT port, though. This was a thing of the late 90s-early 2000s. WinAMP and FAN controlling programs supported that.

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