The QUANCOM® PCITTL32IO TTL Card has 32 I/O lines and is especially useful for the development and prototyping. Inputs and Outputs
The 32 I/O lines kann be programmed as inputs or outputs in blocks of 8 lines. When powering up all lines are set to input type and are passive.Memory vs. I/O Mode
The I/O mode and the memory mode mode can be selected with a jumper setting. Generally the memory mode is the faster and therefore the preferred mode. The I/O mode can be considered as obsolete, as it is slower and slowes down the system due to the fact that it generates wait states.Use of Interrupts
You can define one of the inputs 0 to 15 as interrupt source. A raising and/or falling edge of the input signal can generate an interrupt. This interupt can be routed to a subroutine inside your C or C++ program if the compiler supportes multithreading and pointers. There is a sample in Visual-C/C++ which shows how to incorporate interrupts in your program. Inside C/C++ programs (running in the usermode) up to 3000 interrupts per second are possible. One advantage of interrupts is that you don't need to poll the hardware and this lowers the system load. External circuits and voltage at the D-Sub Connector
The external 68-pin. D-Sub Connector has a +5V voltages pin which can be used to supply external circuits with power. Easily connect your external lines with PAR-KL-68 cable clamp. No knowledge in the driver development required.
We implemented a QLIB (QUANCOM Driver Library) command set which is the same for all operating systems. An application that controls the PCITTL32IO, and which is generated for Windows 98 can be recompiled directly for a Windows 2000 or Windows XP PC. The QLIB simplifies the access of the hardware registers because it allows you to use QLIB commands.
The PCITTL32IO card can be accessed via traditional I/O or with a memory pointer to the hardware registers. The memory pointer is valid within the usermode application. This safes a significant amount of processor time because there is no underlying library function call to the kernel driver is required. Although the use of this feature is only for very fast applications required.