Q4Microprocessor
Question
Q.4. How is the A/D converter interfaced with 8051 microcontroller?
Answer
An A/D converter (such as ADC0808) is interfaced with the 8051 through its 8-bit digital output bus connected to a data port, and its ALE, START, EOC and OE control signals connected to individual I/O pins that the program toggles in sequence to select a channel, start conversion, detect completion, and read the resulting digital value.
The ADC (such as the ADC0808/0809) is interfaced with the 8051 by connecting its 8-bit parallel digital output to an 8051 I/O port (e.g., Port 1), and connecting its control lines — ALE (to latch the selected analog channel address), START (to begin conversion), EOC (End of Conversion, indicating when the digital result is ready), and OE (Output Enable, to enable the ADC's output onto the data bus) — to individual I/O pins of another port. The 8051 program selects the desired input channel and address, pulses ALE and START together to initiate conversion, then either polls the EOC pin in a software loop or uses it to trigger an external interrupt to detect conversion completion, after which it asserts OE and reads the resulting 8-bit digital value from the connected data port.