search

tigard-tools / tigard

An FTDI FT2232H-based multi-protocol tool for hardware hacking
Other
559 stars 65 forks source link

Understanding LA #39

Closed Kabron287 closed 3 years ago

Kabron287 commented 3 years ago

According you explanations and schematic LA has 8 channels xPB0-xPB7. Actually, only 4 channels really works with Sigrok Pulseview: UART_RX-AD1 UART_CTS-AD3 UART_DSR-AD5 UART_DCD-AD6 In theory two more signals could be used: BD2, BD6 And that is all, because rest of the signals are not inputs and could not be switched to inputs. So, as long as PulseView is the only suitable SW, LA is 4 channels width.

Or, I do not understand something? Sch PulseView

securelyfitz commented 3 years ago

The logic analyzer port isn't there to use tigard as a logic analyzer, it's there to use a logic analyzer to inspect the communication between Tigard and your target system.

See the I2C example - if you were working with an I2C device but were having trouble getting a response from the target device, or were getting unexpected/invalid/corrupt data, you could attach the logic analyzer and then examine the i2c protocol and perhaps identify timing or signal strength issues.

Let me know if there's anywhere in the documentation where I could to clarify this to avoid misrepresenting Tigard as a logic analyzer itself. Yes, there is an MPSSE logic analyzer driver in pulseview, but my experience with it has been frustrating at best.

Kabron287 commented 3 years ago

Thanks for answer.

Let me know if there's anywhere in the documentation where I could to clarify this to avoid misrepresenting >>Tigard as a logic analyzer itself.

Obviously - nowhere, but my question is an example of this.

I guess, it could be stated out, say in form you answer me: The logic analyzer port isn't there to use tigard as a logic analyzer, it's there to use another logic analyzer to inspect the communication between Tigard and your target system.

At least my experiment shows the possibility of using the device with PulseView

securelyfitz commented 3 years ago

revised the readme text in e1927e9951568c4fb76dfcf3dc6b9c09ee046816 Do you think the wording is more clear now?

The MPSSE logic analyzer driver appears to work nicely, but my experience is that the timing and data rate has LOTS of jitter, making signals not come out anything like expected. Ideally there should be a better clock source on an FT2232H intended for logic analyzer usage - though that might be doable on the existing headers and may require some firmware...

Kabron287 commented 3 years ago

Crystal clear

securelyfitz commented 3 years ago

great. You're not the first to ask a similar question, so glad to get it documented clearly.