The EM78611 is a series of Universal Serial Bus 8-bit RISC microcontrollers. It is specifically designed for USB low speed device application and to support legacy device such as PS/2 keyboard. The EM78611 also support one device address and three endpoints. With no firmware involved, these series of microcontrollers can automatically identify and decode Standard USB Command to EndPoint Zero. The EM78611 is implemented on a RISC architecture. It has eight-level stack and six interrupt sources. Each device has 144 bytes of general purpose SRAM and 6K bytes of program ROM. The EM78611 has up to 13 pins with the capacity of sinking large current. It also has dual clock mode which allows the device to run on very low power saving frequency

Features

• Operating voltage 4.4V ~ 5.25V  
• Low-cost solution for low-speed USB devices, such as keyboard, joystick, and Gamepad.  
• USB Specification Compliance 
  * Universal Serial Bus Specification Version 1.1 
  * USB Device Class Definition for Human Interface Device (HID), Firmware Specification Version 1.1 
  * Support 1 device address and 3 endpoints  
• USB Application
  * P75(D-) has an internal pull-high resistor (1.5K Ohm) 
  * USB protocol handling 
  * USB device state handling 
  * Identifying and decoding of Standard USB commands to EndPoint Zero
• PS/2 Application Support 
  * Auto-detects PS/2 or USB port 
  * Build-in PS/2 port interface for keyboard and mouse
• Built-in 8-bit RISC MCU 
  * 8 level stacks for subroutine and interruption 
  * Six available interruptions
  * 8-bit real time clock/counter (TCC) with overflow interruption
  * Built-in RC oscillator free running for WatchDog Timer and Dual clock mode
  * Two independent programmable prescalers for WDT and TCC 
  * Two methods of saving power:
     - Power-down mode (SLEEP mode)
     - Dual clock mode.
  * Two clocks per instruction cycle 
• I/O Ports 
  * Up to 13 LED sink pins 
  * Each GPIO pin of Ports 5, 6, 8, and 9; has an internal programmable pull-high resistor (25K Ohm)
  * Each GPIO pin of Port 6, P74~P77, and Port 9 can wakeup the MCU from sleep mode by input state change
• Internal Memory
  * Built-in 6K*13 bits Program ROM
  * Built-in 144 bytes general purpose registers (SRAM)
  * Built-in USB Application FIFOs.
• Operation Frequency
  * Normal Mode: MCU runs at the external oscillator frequency; 6MHz or 12MHz
  * Dual Clock Mode: MCU runs at the frequency of 256KHz (or 32KHz, 4KHz, 500Hz),
  emitted by the internal oscillator with the external ceramic resonator (or crystal) turned off to save power.
• Built-in 3.3V Voltage Regulator
  * For MCU power supply
  * Pull-up source for the external USB resistor on D-pin.
• Package Type:
  * 40 pin PDIP (EM78611AP)
  * 44 pin QFP (EM78611AQ)

• USB Keyboard only.
• USB and PS/2 both compatible with Keyboard.
• USB Keyboard with USB Mouse.
• USB Joystick.