CMX850 Communications Controller

The CMX850 combines a dual-port V.22bis modem with an 8051 microcontroller including 8k of RAM to form a powerful communications processor.
Extended addressing offers page-mode access to 4Mbytes of external FLASH memory.
The 8051 runs from the ~12MHz oscillator with a choice of sub-multiple frequencies down to ~12kHz giving a range of low power operating modes.
The supply voltage is in the range: 3.0 to 3.6 V.
A watchdog timer and standard 8051 timers are included.
I/O facilities include an LCD controller interface, 8x16 keypad interface with interrupts, a UART, two low power PWM outputs, and a multiplexed 2-input 10-bit A to D converter. Unused functions can be alternatively used as GPIO. Low power and very low power (sleep) modes contribute to low battery consumption.
The MUXAD pin allows the 8051 to multiplex the eight lower address and data bus lines to release further pins for I/O (debug support etc.).
The V.22bis modem can be woken from sleep mode by ringing or line-reversals.