Rainbow Electronics MAX1401 - Manual (Page 32)

Bit-Banging Interface (80C51, PIC16C54)
Any microcontroller can use general-purpose I/O pins
to interface to the MAX1401. If a bidirectional or open-
drain I/O pin is available, reduce the interface pin count
by connecting DIN to DOUT (Figure 13). Listing 2
shows how to emulate the SPI in software. Use the
same initialization routine shown in Listing 1.
For best results, use a hardware interrupt to monitor the
INT pin and acquire new data as soon as it is available.
If hardware interrupts are not available, or if interrupt
latency is longer than the selected conversion rate, use
the FSYNC bit to prevent automatic measurement while
reading the data output register.
MAX1401
+3V, 18-Bit, Low-Power, Multichannel,
Oversampling (Sigma-Delta) ADC
32 ______________________________________________________________________________________
V DD
P3.0
P3.1
RESET
DOUT
DIN
SCLK
CS
8051
MAX1401
Figure 13. MAX1401 to 8051 Interface
Listing 2. Bit-Banging SPI Replacement