| 摘要 |
PURPOSE:To speedily check the acceptance or reject of a chip by adding a test terminal to the chip, switching a normal operating mode and a test mode, and directly outputting digital and analog signals in the chip to a port in the test mode. CONSTITUTION:The controller has the test terminal 31 provided on the chip, a digital and analog ports 51 to 58. When the test terminal 31 is at one logical level, a CPU and circuits, all of which are integrated in the chip, are instructed to execute normal operation. Conversely, when the test terminal 31 is at the other logical level, that is, the test mode, digital input signals of a D/A converter 4 are outputted to output ports 38 to 46 for LED display, and D/A- converted by the D/A converter 4. Their analog signals are outputted to the analog port 58. In such a way, the digital input signal and analog output signal of the D/A converter 4 can be fetched to the outside only by changing the level of the test terminal 31. Thus, checking the operation of the chip is facilitated. |
