Hi,

I am trying to develop PC based Dialler using MT8888 Transreceiver interfaced with 80C51.

Can you give source code in C how to interface the MT8888.

Specially I donot know how select the Control Register CRA & CRB bits

If there any example code in c please suggest me

Thanks
Prev Ravanth

 

CRA and CRB are both at the same address. You need to read the datasheet carefully. Here is the appropriate excerpt

The microprocessor interface provides access to five
internal registers. The read-only Receive Data
Register contains the decoded output of the last
valid DTMF digit received. Data entered into the
write-only Transmit Data Register will determine
which tone pair is to be generated (see Table 1 for
coding details). Transceiver control is accomplished
with two control registers (see Tables 6 and 7), CRA
and CRB, which have the same address. A write
operation to CRB is executed by first setting the
most significant bit (b3) in CRA. The following write
operation to the same address will then be directed
to CRB, and subsequent write cycles will be directed
back to CRA. The read-only status register indicates
the current transceiver state (see Table 8).​

http://www.datasheetarchive.com/search.php?q=MT8888&sType=part
​