micro:bit as Pass / Fail indicator in an automated test setup

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Fri, 25 Jan 2019 22:06:22 GMT

With some changes - none of them intrusive or complex - this design can become a binning device.

You can put an instrument at the start of the cycle that evaluates the device under test and gives it a binning grade.

One example is for a transistor (this is used by manufacturers to give it a postfix A, B or C)

hfe < 80,
hfe between 80 and 120,
hfe > 120

The micro:bit can then - instead of rejecting or passing the device as it's doing in the blog's design - push it into the right bin.

Now that I have a meter with binning and automation capability (DMM6500) I may take this design further and turn it into a binning line driver.

I bet it 'll be less than 20 lines of code to change.

Hang on ...

RE: micro:bit as Pass / Fail indicator in an automated test setup

Workshopshed — Fri, 30 Nov 2018 21:35:47 GMT

Great stuff. I knew that the Microbit would work with MBed but I've never seen a worked example before.

I had to google the meanining of SCPI https://www.rohde-schwarz.com/us/driver-pages/remote-control/remote-programming-environments_231250.html

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Wed, 07 Nov 2018 20:44:51 GMT

You should be able to import the firmware project in Mbed from my repository.

In Mbed, click import. Then click on the link to import from URL as hown in the capture below:

[View:/resized-image/__size/728x186/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/contentimage_5F00_189088.png:728:186]

Enter https://os.mbed.com/users/jancumps/code/microbit_scpi_pass_fail/

Select the options as shown below:

[View:/resized-image/__size/410x267/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/contentimage_5F00_189089.png:410:267]

After Import, you can select the project and press compile.

If all works OK, Mbed creates a hex file and places it in your Download folder.

If you drop that file on your micro:bit, it should be programmed as a Pass / Fail device.

You can test this by connecting to its COM port with puTTY, 115200.

type STA PAS then enter (you don't see what you type)

It should show a + on the led matrix.

I'd appreciate if anyone with a micro:bit can test this.

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Tue, 06 Nov 2018 19:58:37 GMT

Yay! I have the LabVIEW driver developed and working.

[View:/resized-image/__size/588x229/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/8055.contentimage_5F00_189086.png:588:229]

I made blocks to control the status. You see it used three times in the image above, to test each state.

In real flows, you'd use this in a conditional block based on the success or failure of a test process.

I've also made utility driver blocks for init, close and reset.

All in all this device is fairly easy to use in an automation.

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Mon, 05 Nov 2018 23:49:11 GMT

Last update for the day: the GPIO is implemented. That was very easy.

[View:/resized-image/__size/520x390/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/contentimage_5F00_189085.png:520:390]

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=++++++++case+SCPI_STATE_PASS%3A%0A++++++++++++uBit.io.P1.setDigitalValue%280%29%3B%0A++++++++++++uBit.io.P0.setDigitalValue%281%29%3B%0A++++++++++++uBit.display.clear%28%29%3B%0A++++++++++++uBit.display.print%28imgPass%29%3B%0A++++++++++++retval+%3D+SCPI_RES_OK%3B%0A++++++++++++break%3B%0A++++++++case+SCPI_STATE_FAIL%3A%0A++++++++++++uBit.io.P0.setDigitalValue%280%29%3B%0A++++++++++++uBit.io.P1.setDigitalValue%281%29%3B%0A++++++++++++uBit.display.clear%28%29%3B%0A++++++++++++uBit.display.print%28imgFail%29%3B%0A++++++++++++retval+%3D+SCPI_RES_OK%3B%0A++++++++++++break%3B%0A++++++++case+SCPI_STATE_CLEAR%3A%0A++++++++++++uBit.io.P0.setDigitalValue%280%29%3B%0A++++++++++++uBit.io.P1.setDigitalValue%280%29%3B%0A++++++++++++uBit.display.clear%28%29%3B%0A++++++++++++retval+%3D+SCPI_RES_OK%3B%0A++++++++++++break%3B]

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Mon, 05 Nov 2018 23:02:53 GMT

little demo:

[View:https://www.youtube.com/watch?v=5um1LvclLbA:740:466]

A short video where I shoot SCPI Pass, Clear and Fail commands. The display shows the respective states.

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Mon, 05 Nov 2018 22:09:02 GMT

I've got most things working now:

listen to USB commands in sleep mode
parse and execute SCPI commands
Show a bitmap (in this case a X or a +) on the display

[View:/resized-image/__size/816x612/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/contentimage_5F00_189083.png:816:612]

The remaining things are the two GPIO pins and implementing the SCPI command to set Pass Fail or Clear status

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Mon, 05 Nov 2018 16:04:15 GMT

The program can now read serial input.

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=%23include+%22MicroBitSerial.h%22%0A%2F%2F+...%0AMicroBitSerial+serial%28USBTX%2C+USBRX%29%3B+%0A%2F%2F+...%0A+++while%281%29+%7B%0A++++++++character+%3D+serial.read%28%29%3B%0A++++++++SCPI_Input%28%26scpi_context%2C+%28const+char+*%29+%28%26character%29%2C+1%29%3B%0A++++%7D]

[View:/resized-image/__size/670x115/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/contentimage_5F00_189082.png:670:115]

RE: micro:bit as Pass / Fail indicator in an automated test setup

Jan Cumps — Mon, 05 Nov 2018 13:52:49 GMT

I unpacked the micro:bit today and tried if I can create a C program that uses the SCPI library.

This works. I was able to run a SCPI parse test set and stream the results to USB.

[View:/resized-image/__size/692x319/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-eaf0e971-5fc8-4ea0-af1e-78139ab905ee/contentimage_5F00_189081.png:692:319]

It's a small step. I'm using the fprintf() function to show the results and have not listened to any input yet.

I'll most likely have to work with the micro:bit USB C++ API. I'll investigate that...