Drive unit and liquid crystal device

A drive unit which receives display data from a microprocessor unit to drive a displaying section, comprising:

• memory for storing display data to be used for image display in said displaying section;
• an arbitration circuit for receiving a first access request forming a request for access to said memory according to a command from said microprocessor unit and a second access request forming a request for access to said memory according to a displaying operation in said displaying section to arbitrate in priority between said first and second access requests for starting an access operation to said memory according to the preferential one of said first and second access requests;
• a memory control circuit for conducting a precharge operation for said memory before the start of said access operation to the memory;
• and
• decision means for making a decision as to whether or not said memory precharge operation reaches completion,
• wherein said arbitration circuit starts said memory access operation according to one of said first and second access requests on condition that the decision is made to the completion of said memory precharge operation.

A liquid crystal device, comprising:

• a drive unit which receives display data from a microprocessor unit to drive a displaying section, the drive unit comprising:
• a memory for storing display data to be used for image display in said displaying section;
• an arbitration circuit for receiving a first access request forming a request for access to said memory according to a command from said microprocessor unit and a second access request forming a request for access to said memory according to a displaying operation in said displaying section to arbitrate in priority between said first and second access requests for starting an access operation to said memory according to the preferential one of said first and second access requests;
• and
• a circuit for outputting, to an external terminal, a memory access monitor signal for monitoring an access condition to said memory to which an access operation starts in accordance with the arbitration of said arbitration circuit;
• and
• a liquid crystal display panel to be driven by said drive unit.

A liquid crystal device, comprising:

• a drive unit which receives display data from a microprocessor unit to drive a displaying section, the drive unit comprising:
• a memory for storing display data to be used for image display in said displaying section;
• an arbitration circuit for receiving a first access request forming a request for access to said memory according to a command from said microprocessor unit and a second access request forming a request for access to said memory according to a displaying operation in said displaying section to arbitrate in priority between said first and second access requests for starting an access operation to said memory according to the preferential one of said first and second access requests;
• a memory control circuit for conducting a precharge operation for said memory before the start of said access operation to the memory;
• and
• decision means for making a decision as to whether or not said memory precharge operation reaches completion,
• wherein said arbitration circuit starts said memory access operation according to one of said first and second access requests on condition that the decision is made to the completion of said memory precharge operation;
• arid
• a liquid crystal display panel to be driven by said drive unit.

A liquid crystal device, comprising:

• a drive unit which receives display data from a microprocessor unit to drive a displaying section, the drive unit comprising:
• a memory for storing display data to be used for image display in said displaying section;
• and
• an address control circuit, when said microprocessor unit sets a first start address and a first end address related to a first address, forming one address of a column address and a row address of said memory, for access to a specified display area of said memory and starts an access operation to said memory, automatically varying said first address to return said first address to said first start address on condition that said first address goes beyond said first end address and further varying a second address forming the other address of said column address and said row address;
• and
• a liquid crystal display panel to be driven by said drive unit.

A liquid crystal device, comprising:

• a drive unit which receives display data from a microprocessor unit to drive a displaying section, the drive unit comprising:
• a memory for storing said display data from said microprocessor unit;
• and an arbitration circuit for receiving a first access request forming a request for access to said memory according to a command from said microprocessor unit and a second access request forming a request for access to said memory according to a displaying operation in said displaying section to arbitrate in priority between said first and second access requests for starting an access operation to said memory according to one of said first and second access requests,
• wherein, when a competition occurs between said first and second access requests, said arbitration circuit gives priority to said first access request;
• and
• a liquid crystal display panel to be driven by said drive unit.