The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Some older Hauppauge WinTV PCI TV tuner cards can be modified to expose 24 GPIO ports from a Brooktree BT848, BT849, BT878 or BT879 chip. This is a hardware hack—not a standard 24-pin header found on every tuner card—and accessing the chip’s tiny pins requires delicate soldering. On Linux, the related driver is bt8xxgpio.
What “24-port GPIO on a PCI card” means
The idea, described by Brian Benchoff in a March 2, 2013 Hackaday project article, is to repurpose a compatible PCI TV tuner card as a source of GPIO for an x86 computer. The article identifies Hauppauge WinTV cards built around Brooktree BT848, BT849, BT878 or BT879 video-capture chips. Linux’s documentation for bt8xxgpio likewise describes 24 digital GPIO ports on the BT8xx chip.
The card is not a purpose-built GPIO accessory with a ready-made 24-pin connector. The project involves physically wiring the chip’s GPIO pins out, for example with magnet wire. The Linux documentation’s search excerpt describes the package as small and the soldering as advanced; the kernel page’s full procedure is not established here, so treat the cited project as a concept to investigate, not a complete board-specific wiring guide.
How to assess a tuner card before modifying it
- Identify the chip. Check the tuner card itself and any reliable documentation for its exact Brooktree part number. The relevant models named in the project are BT848, BT849, BT878 and BT879. A PCI tuner card without one of these chips is not shown to be compatible.
- Check the actual board. Board layouts can vary, and the cited sources do not verify every card variant. Confirm that the chip and its pins are accessible and that you can establish the pin mapping for that specific board before soldering.
- Confirm the software path. The Linux driver associated with this family is
bt8xxgpio. The 2013 article’s general wording about Linux distributions does not establish support in every current distribution, so check the driver and your intended system rather than assuming it will work. - Decide whether the soldering is within your skill level. The project calls for magnet wire and a soldering iron; the chip’s small package makes precision work important. If you need a plug-in accessory or cannot verify the wiring, choose a purpose-built digital I/O card instead.
- Check the host. This is a PCI card approach, so verify that the target computer has a compatible PCI slot. Do not assume a current desktop or small x86 board has one.
What the available sources do—and do not—establish
The BT8xx documentation establishes the 24-port capability of the chip, not a complete electrical specification for a particular modified tuner card. The cited project and kernel material do not establish GPIO speed, current capacity, voltage tolerance, protection circuitry, reliability, or compatibility for every card. Do not transfer specifications from a different PCI I/O product to this modification.
#1 Best Overall
- MCS9922 Chipset
- Compatible with Industrial Standard 16C550 UART. On Chip 256-byte Depth FIFO in Transmit.
- Transfer data rates up to 250Kbps on each port. Supports hardware and software flow control. Supports 5, 6, 7, 8-bit Serial format
- Fully compliant with PCI-Express base Specification Revision 1. 0a
- Single-lane (x1) PCI-Express with throughput up to 2. 5Gbps
No project-specific benchmark or current market-availability figure for the BT8xx tuner-card hack is established by the cited material. Treat performance, electrical limits and sourcing as open questions until verified for the exact chip, board and operating system you plan to use.
A documented alternative: a purpose-built PCI digital I/O card
If you need published electrical specifications rather than an improvised tuner-card modification, Measurement Computing’s PCI-DIO24/S is a separate, purpose-built PCI digital I/O board. Its February 2010 revision 1.1 specification lists 24 I/O lines, Ports A0–A7, B0–B7 and C0–C7, an 82C55 interface and a 37-pin connector. It is not the BT8xx hack and its specifications say nothing about the electrical behavior of a modified TV tuner card.
Rank #2
- 1. PCIE-SE2 allow users add 2X RS232 BD9 serial Ports on desktop PCs or industrial devices by motherboard PCI Express slot.
- 2. Seamless connect to serial DB9 ports device such as POS system, industrial testing and control device, security system, logistic management equipment, scanners and printers.
- 3. Need to install driver on Windows XP, Vista, 7, 8.x, 10, 11 (32/64bit) systems. Linux kernel 2.6.x, 3.x, 4.x, 5.x need to refer compile source code from the driver CD.
- 4. Selected by ASIX AX99100 solution supports on chip 256-byte depth FIFO in transmit. Works on Intel, AMD, ARM hardware platform.
- 5. The full-size bracket on this expansion card will works on standard size PCs. The 2X low profile bracket for slim PCs. Based on PCIE X1 interface, will works on X1, X4, X8, X16 slot.
| Consideration | BT8xx tuner-card modification | Measurement Computing PCI-DIO24/S |
|---|---|---|
| What it is | A modification to a PCI TV tuner card with a named BT8xx chip; not a standard GPIO header card. | A purpose-built PCI digital I/O card. |
| I/O count | 24 digital GPIO ports are attributed to the BT8xx chip by the Linux kernel documentation; the modified board’s electrical behavior is not specified here. | 24 I/O lines, Ports A0–A7, B0–B7 and C0–C7, per Measurement Computing’s 2010 specification. |
| Physical connection | Individual chip pins must be wired out; the cited material does not specify a standard connector for the modification. | 37-pin connector, per the 2010 specification. |
| Electrical limits | Not established for the modified tuner card by the cited sources. | The 2010 PCI-DIO24/S specification lists input low at 0.8 V maximum and input high at 2.2 V minimum, among other model-specific specifications. |
| Host requirement | Requires a compatible PCI slot and a card with the relevant BT8xx chip. | PCI; the 2010 specification lists universal PCI keying for 3.3 V or 5 V signaling environments. |
The PCI-DIO24/S guide says its I/O lines power up or reset as high-impedance inputs and warns not to connect high-current or high-voltage devices directly because the board may be damaged. Those cautions apply to that product only. Consult its own documentation for wiring and operating limits; they are not safety limits for the tuner-card modification.
Quick Recap
Best Value
- RIITOP USB PCIe to 20Pin+ Type-E Card is a PCIe x1 interface to 1x 20Pin (19+1xempty) USB 3.0 header + 1x Type-E (A Key) USB C Header expansion card. 1x 20Pin (19+1xempty) USB 3.0 header will extend to 2x USB-A ports on front panel of Desktop PCs . 1x Type-E (A Key) USB C Header will expand 1x USB-C Port. You may add 2x 5Gbps max USB-A ports and 1x USB-C Port only via 1x PCI-e Slot on your old motherboard
- [Built-in 5Gbps Chipset With Heatsink] RIITOP USB 3.0 PCIe Adapter adopts VIA VL805, total 5Gbps bandwidth. The advanced Heatsink will help the chipset working in lower temperature, avoid having any issues with reliability due to overheating
- Hardware Requirement: RIITOP USB Expansion Card adopts PCIe x1 design, it can work on PCIe 3.0/4.0 x1, X4, X8, X16 slot, but do not work on any PCI slot. And coming with Both full-size and Half-size brackets will work on Standard Size and Mini PCs
- Easy to install: RIITOP PCIe to 20Pin + Type-E Host Internal card can be inserted to PCIe slot on MB, no additional power supply to connect. Please Note: The card can not be connected with any External USB Device directly, You may have 20pin or Type-E Front Panels to work with it together
- Compatible OS: Plug and Play on Windows 11, 10, 8.x (32/64bit) and Windows Server 2012, 2012R2, 2016, 2019, 2022 systems. But Need to Install Driver on Windows XP, Vista, 7 (32/64bit) and Windows Server 2003, 2003R2, 2008, 2008R2 (32/64bit) systems
Rank #4
- 1 PORT SERIAL CARD: Serial controller card w/ 16950 UART based on ASIX AX99100, allows 1x DB9 port w/bi-directional RS232 speeds up to 921.6Kbps per port, available 256 byte FIFO buffer & 9th data bit; Upgraded version of our popular card PEX1S952LP
- OPTIONAL CONFIGURABLE POWER: PCI Express RS232 serial adapter card provides choice of 12v, 5v, or none through pin 9 w/up to 2A total
- STANDARD PROFILE & LOW PROFILE BRACKET: PCIe serial card comes w/ a low profile bracket pre-installed & 1x full profile bracket is incl for versatile install; Supports Windows & Linux
- VERSATILE APPLICATIONS: For low/standard profile desktop/servers w/ uses in point of sale terminals, PLCs, control/automation in factories, scientific sensors, medical equipment, scanner, oscilloscope
Rank #3
- Dual Serial Ports: Provides two independent RS232 serial ports, enabling connections with multiple serial DB9 port (RS232 communication) devices, significantly expanding your system's connectivity.
- Wide Compatibility: Requires driver installation for Windows XP, Vista, 7, 8.x, 10, 11 (32/64-bit) systems. For Linux kernels 2.6.x, 3.x, 4.x, 5.x, source code on the driver CD can be compiled.
- Advanced Chip Solution: Utilizes the ASIX AX99100 solution supporting 256-byte depth FIFO transfer on-chip, suitable for Intel, AMD, and ARM hardware platforms.
- Versatile Bracket Design: Comes with a full-size bracket for standard PCs and a low-profile bracket for 2U computers. Compatible with PCIe x1 slots and also fits x4, x8, x16 slots.
- Important Notes:Ensure your computer has an available PCIe slot,for 2U computers, manually replace with the low-profile bracket,for desktop computers, install the correct driver from the Mini-CD.
Which approach fits your project?
- Consider the tuner-card hack if you have a verified BT848, BT849, BT878 or BT879 card, a compatible PCI host, Linux driver access you have checked, and the soldering skill to work on fine-pitch chip pins.
- Consider a specified I/O card if you need a documented connector and model-specific electrical limits, and can use a PCI board. The PCI-DIO24/S specifications are historical documentation; current availability is not established here.
- Do not choose either based on assumed pin tolerance or drive strength. The cited evidence does not provide those limits for the modified BT8xx card, and the PCI-DIO24/S figures belong only to that model.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
