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Topic: [solved] OpenBench LA + Bus Pirate: LA doesn't work (Read 1545 times) previous topic - next topic

[solved] OpenBench LA + Bus Pirate: LA doesn't work

Hi all,

I wanted to debug the signal sent from the Bus Pirate to an EEPROM chip. The chip wasn't replying, so I decided to investigate with the OpenBench LA. However, I couldn't make it work very well.

Here is a typical example:
I connected directly the pins from the BusPirate to the Logic analyzer and I put a trigger on CS. When I disable the CS, the OLA doesn't see it and doesn't fire the trigger :/. So I took a voltmeter and I measured directly on the pins of the OLA: when the CS is disable, it goes up to 200mV and 0V when active.
The same is happening with the clock, I am not able to intercept it.

So what is the sensitivity of the OLA ? Should I amplify the signal before using the OLA ?

Thanks for your reply,

C0

EDIT: trigger on "Power Supply ON/OFF" works great, but here we have 3.3V.
EDIT2: I updated everything possible, so I have all the latest versions for the OLA (& bus pirate).

Re: OpenBench LA + Bus Pirate: LA doesn't work

Reply #1 –
I think your problem is in the setup of the buspirate.

Do you have a connection between Vpu and 3v3? (I'm guessing  you are connecting to a 3v3 chip). The pins (cs/data/clk) are HiZ when high and tied to GND when low. These lines are connected to Vpu through a resistor. When using 3v3 logic Vpu needs to be connected to 3v3 out. To enable the pullup resistor use the command 'P'

From the manual: http://hackaday.com/2009/07/01/mixed-vo ... us-pirate/ and http://dangerousprototypes.com/2009/07/ ... resistors/

The aux port is not HiZ so you could also test with that pin (a/A command (hi/lo or g (PWM generator)

Re: OpenBench LA + Bus Pirate: LA doesn't work

Reply #2 –
Thanks a lot for your quick reply !
Indeed, you were right, I had my BP misconfigured. It shows me that I still have plenty of things I still not really understand :(.

Thanks a lot !

C0

Re: OpenBench LA + Bus Pirate: LA doesn't work

Reply #3 –
No  problem. This reminds us about the (same) path we walked ;)