AD574 and RS-232C interface circuit

In many applications, it is required to send the A/D conversion results of analog signals to the computer through the computer's serial interface (RS-232C)
. For this purpose, an A/D conversion connected to the RS-232C interface has been designed. The interface circuit is shown in Figure 27-9: As can be seen from the circle, this
is an intelligent interface controlled by a microcontroller. Standard RS-232 C communication is implemented between the computer and the microcontroller 89C2051.
The parallel A/D interface connection is realized between the single chip microcomputer 89C2051 and AD574. Under normal circumstances. AD 574 - has been working. The A/
D is started by 89C2051. After the A/D conversion is completed, it will automatically request an interrupt to the microcontroller. After the microcontroller responds to the interrupt, it will take away the AJD conversion result and save it in the
internal RAM. Start it. A rvD conversion. This process continues in a loop, and the computer can
read the A/D conversion results to the 89C2051 at any time according to actual needs. The disadvantage is that due to the influence of the serial communication baud rate, the update speed of the AlD data is limited.