Robust LCD controller
AssigneeFreescale Semiconductor, Inc.
InventorsHo Sang Au, Kam Tim Cheung
Life of this patent
Estimating the term…
Abstract
An LCD controller (10) has a DMA unit (18) and a FIFO memory (20) for storing display data. The LCD controller also has a display data generator (26) that generates display information using a line of the display data stored in the FIFO memory in accordance with a predefined algorithm. A holding register (28) is connected to the display data generator and stores the generated display information. A multiplexer (34) selects for display either the data stored in the FIFO memory or the generated display information. The generated display information is selected when there is a bus overload indicating that the data stored in the FIFO may be erroneous.
Claims16
A video display controller, comprising:
- a memory unit that receives display data from an external bus and temporarily stores the display data;
- a data converter connected to the memory unit for receiving the display data therefrom and converting the display data to a converted data having a predetermined format;
- a display data generator connected to the data converter for receiving the converted data and generating temporary display data therefrom using a predefined algorithm;
- a holding register connected to the display data generator for storing the generated temporary display data;
- and
- a multiplexer connected to the data converter for receiving the converted data and the holding register for receiving the generated temporary display data, wherein the multiplexer selects and outputs one of the converted data and the generated temporary display data in accordance with a bus overload signal that indicates a predetermined condition of the external bus.
A LCD controller that receives display data from an external bus and provides modified display data to an LCD, the LCD controller comprising:
- a DMA controller connected to the external bus for fetching and receiving display data transmitted over the external bus;
- a FIFO memory connected to the DMA controller for receiving and temporarily storing the display data;
- a data converter connected to the FIFO memory for receiving the display data therefrom and converting the display data to converted data having a predetermined format;
- a display data generator connected to the data converter for receiving the converted data and generating temporary display data therefrom using a predefined algorithm;
- a holding register connected to the display data generator for storing the generated temporary display data;
- a multiplexer connected to the data converter for receiving the converted data and the holding register for receiving the generated temporary display data, wherein the multiplexer selects and outputs one of the converted data and the generated temporary display data in accordance with a bus overload signal that indicates a predetermined condition of the external bus;
- and
- an interface logic unit connected to the multiplexer for receiving the multiplexer output signal and reformatting the multiplexer output signal in accordance with a predetermined display format and providing the reformatted output signal to the LCD.
A method of processing display data received from a bus and provided to a LCD, the method comprising the steps of:
- receiving display data from an external bus and storing the received display data in a memory unit;
- reading the display data stored in the memory unit;
- converting the read display data to a predetermined format;
- providing the formatted display data to a first input of a multiplexer and to a display data generator;
- the display data generator generating temporary display data using the formatted display data in accordance with a predefined algorithm;
- storing the generated temporary display data in a holding register;
- providing the temporary display data from the holding register to a second input of the multiplexer;
- selecting by the multiplexer one of the formatted display data and the generated temporary display data in accordance with a bus overload signal;
- and
- outputting the selected data to a display device.
Dependencies are inferred from the claim text.