Abstract: Apparatus for providing multiple of discrete voltage levels to drive a liquid crystal display (LCD) from an LCD module on board a microcontroller chip includes a charge pump with a switched-capacitor that develops the discrete voltages as multiples of the value of a base voltage that remains substantially without change irrespective of change in the supply voltage. A switched-capacitor charging circuit selectively charges a capacitor to produce successive additive charges individually retrievable from the capacitor. An LCD drive selectively transmits the discrete voltage levels to activate the LCD according to status of an external system under the control of the microcontroller. Voltage losses that may occur during the switched-capacitor charging are compensated to maintain the levels of the discrete voltages free of decay.

Abstract: A microcontroller and associated EPROM program memory are fabricated in a single semiconductor chip. The microcontroller device is adapted to be programmed using digital command words or other bit patterns applied as inputs after installation of the device in circuit with a system to be controlled by the device, and to have its programming pins isolated from the system to avoid effects on system operation while the programming is taking place. The in-circuit programming uses considerably less than the total number of input/output (I/O) pins of the device, which in total are fewer than the number of bits in a command word. This is achieved with a serial/parallel programming interface between the pins and the program memory, and by applying the data in serial fashion to the interface where it is latched and loaded in parallel in the memory. Input data to the device may alternatively be entered in parallel to the interface in bytes of width less than the total number of I/O pins of the device.

Abstract: A semiconductor microcontroller device is adapted to control the operation of an external system. The device includes a CPU, program memory for storing instructions to be executed by the CPU to perform its control functions, and data memory for storing data for selective retrieval by the CPU. The contents of either memory are code protected by an EEPROM fuse, and are automatically erased if the code protect state of the EEPROM fuse is sought to be reset, and the EEPROM fuse is reset only after the erasure of the memory contents.

Abstract: A single chip, semiconductor microcontroller device is adapted to control an aspect of the operation of an external system. The device includes a CPU, program memory for storing instructions to be selectively executed by the CPU to perform the control functions, and peripheral EEPROM data memory adapted to be written to for storing selected data in selected ones of a multiplicity of addresses of the data memory and for selective retrieval of the stored dam by the CPU within its control function. Internal logic in the device is implemented to abort a write operation in progress on the EEPROM data memory upon occurrence of an asynchronous reset of the device. An error flag is set by the logic to indicate that the write operation is being aborted, and the data that was partially written to the EEPROM memory at the time the write operation was aborted is held intact.