Advanced Microprocessor & Interfacing

8254 is a device designed to solve the timing control problems in a microprocessor. It has 3 independent counters, each capable of handling clock inputs up to 10 MHz, and size of each counter is 16 bit. It operates in +5V regulated power supply and has 24 pin signals. All modes are software programmable. The 8254 is an advanced version of 8253 which did not offered the feature of read back command.  8254 Architecture/ B asic Block Diagram The architecture/  basic block diagram  of 8254 looks as follows − 8254 Pin Description Here is the pin diagram of 8254 − Pin Diagram 8254 In the above figure, there are three counters, a data bus buffer, Read/Write control logic, and a control register. Each counter has two input signals - CLOCK & GATE, and one output signal - OUT. Data Bus Buffer It is a tri-state, bi-directional, 8-bit buffer, which is used to interface the 8253/54 to the system data bus. It has three basic functions − Programming the modes of 8253/54. Loading the count regis