| 摘要 |
PURPOSE:To shorten a check time by indicating data, which should be supplied from one group of digital ports to a D/A converter, through a CPU at the time of setting a test terminal to the other logical level, and taking out data from the other group of digital ports, and taking out the output of the D/A converter from analog ports. CONSTITUTION:The input value of a specific digital port is written in latches 21 to 24 as latch data at the time of testing, and an arbitrary value is set to the outside of a chip to check the chip. Simultaneously, the output of a D/A converter 4 is directly outputted to one port of an analog multiplexer 8, and digital input data of the D/A converter 4 is directly outputted to an output port (LED port). Thus, a CPU, latches 21 to 24, and the D/A converter 4 are checked in a short time. |
