Datasheet

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SBAS124C − DECEMBER 1999 − REVISED DECEMBER 2005
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APPLICATION INFORMATION
Intel 80C51
The Intel 80C51 operated in serial port mode 0 has a two-wire (three-wire if an additional I/O pin is used for CS)
serial interface. The TXD pin provides the clock for the serial interface and RXD serves as the data input and
output. The data is transferred LSB first. Best compatibility is achieved by connecting the RISE/FALL pin of the
ADS7870 high (rising edge of SCLK active). In the Interface Configuration register, the LSB bit and the 8051
bit should be set. The 2W/3W bit should also be set. The first instruction after power-on or reset should
be a write operation to the Interface Configuration register.
Figure 42 shows a typical physical connection between an 80C51 and an ADS7870. CS may be permanently
tied low if desired, but then the ADS7870 must be the only peripheral.
80C51 ADS7870
RXD
TXD
Px.x
DIN
DOUT
SCLK
CS
10 kΩ typ
V
DD
Figure 42. Connection of an 80C51 to an ADS7870