| 摘要 |
<p>PURPOSE:To reduce the load on a higher-order CPU which controls a touch panel by scanning a switch matrix by hardware and switching hardware to software at the time of detecting turning-on of a key. CONSTITUTION:When a power source is turned on, selectors 1 and 2 are driven with hardware by a control circuit to scan a touch panel 3; and when turning-on of a key is detected, an interrupt signal is generated by a detecting circuit 5 to transfer the control to a microprocessor. The processor reads out all contacts on the panel 3 which are turned on and releases an interrupt mask set for key read and transfers the control to higher-order software and restarts hardware scanning of the panel 3 interrupted at the time of the occurrence of the interrupt signal. Thus, the load on the higher-order CPU which controls the touch panel is reduced.</p> |
