The LM8328 GenI/O - Expander and Keypad Controller is a dedicated device to unburden a host processor from scanning a matrix-addressed keypad and to provide flexible and general purpose, host programmable input/output functions. Three independent PWM timer outputs are provided for dynamic LED brightness modulation.

It communicates with a host processor through an I2C-compatible ACCESS.bus serial interface. It can communicate in Standard (100 kHz) - and Fast-Mode (400 kHz) in slave Mode only.

All available input/output pins can alternately be used as an input or an output in a keypad matrix or as a host programmable general purpose input or output.

Any pin programmed as an input can also sense hardware interrupts. The interrupt polarity (“high to low” or “low to high” transition) is thereby programmable.

The LM8328 follows a predefined register based set of commands. Upon start-up (power - on) a configuration file must be sent from the host to setup the hardware of the device.

• KEY FEATURES
  • Internal RC Oscillator, No External Clock Required
  • Internal PWM Clock Generation, No External Clock Required
  • External Reset for System Control
  • Programmable I2C-compatible ACCESS.bus Address (Default 0x88)
  • Support for Keypad Matrices of up to of 8 x 12 Keys, Plus 8 Special Function (SF) Keys, for a Full 104 Key Support
  • I2C-compatible ACCESS.bus Slave Interface at 100 kHz (Standard-Mode) and 400 kHz (Fast-Mode)
  • Three Host-programmable PWM Outputs for Smooth LED Brightness Modulation
  • Supports General-purpose I/O Expansion on Pins Not Otherwise Used for Keypad or PWM Output
  • 15 byte Key Event Buffer
  • Multiple Key Event Storage
  • Key Events, Errors, and Dedicated Hardware Interrupts Request Host Service by Asserting an IRQ Output
  • Automatic HALT Mode for Low Power Operation
  • Wake-up from HALT Mode on Any Interface (Rising Edge, Falling Edge or Pulse)
  • Three PWM Outputs with Dedicated Script Buffer for up to 32 Commands
  • Register-based Command Interpreter with Auto Increment Address
• HOST-CONTROLLED FEATURES
  • Reset Input for System Control
  • PWM Scripting for Three PWM Outputs
  • Period of Inactivity that Triggers Entry into HALT Mode
  • Debounce Time for Reliable Key Event Polling
  • Configuration of General Purpose I/O Ports
  • Various Initialization Options (Keypad Size, etc.)
• KEY DEVICE FEATURES
  • 1.8V ± 10% Single-supply Operation
  • On-chip Power-on Reset (POR)
  • Watchdog Timer
  • −40°C to +85°C Temperature Range
  • 25-pin DSBGA Package