| ??? 06/05/10 14:32 Read: times Msg Score: +1 +1 Informative |
#176423 - Use loopback and stimuli Responding to: ???'s previous message |
Most digital signals the tester picks up are possible to control by the microcontroller. So the microcontroller can set the signal to both states and the tester tests that it is low when expected to be low and high when expected to be high.
For analog signals, it's good if the tester can multiplex between the test point and some references. A problem is when measuring a voltage that is expected to be 0V - do you measure 0V or do you measure air? If the test point has a reasonable reistance, then you can add a pull-up resistor to the test jig, and have the jig measure the value with and without the pull-up. If you measure a strong signal, the pull-up will affect little. If you measure "air", the pull-up will let you measure the pull-up voltage instead. In the end, loopback or programmable stimuli, should be able to cover almost all parts of the test jig and tested measurement points. Todays very fast and cheap micrcontrollers allows many test points to be handled concurrently without need for expensive instruments, so having an extra step or two for each test point need not affect the total testing time too much. |
| Topic | Author | Date |
| test the test jig | 01/01/70 00:00 | |
| only ISO believes ... | 01/01/70 00:00 | |
| "Calibration" | 01/01/70 00:00 | |
| ISO9000, concepts and lies | 01/01/70 00:00 | |
| doghouse and flagpole | 01/01/70 00:00 | |
| I agree... | 01/01/70 00:00 | |
| Use loopback and stimuli | 01/01/70 00:00 | |
| "Design For Test" (DFT) | 01/01/70 00:00 | |
| You can not ask us | 01/01/70 00:00 | |
| Yes but... | 01/01/70 00:00 | |
| No silver bullet | 01/01/70 00:00 | |
| Calibrations... NIST traceability.... fun | 01/01/70 00:00 | |
| That is what traceable means | 01/01/70 00:00 | |
| Should be few steps to a national reference | 01/01/70 00:00 | |
| Article on the topic | 01/01/70 00:00 | |
Test the test harness | 01/01/70 00:00 |