USBi question

There was actually a firmware update to the USBi very recently to fix SPI communication with our AD1871 codec. However, this is not likely the source of your problems, because it did not affect the operation of the USBi with any of the other SigmaDSP devices in any way.

Have you sat down and done a side-by-side comparison of the boards? Basically, I think you need to perform 4 tests using two USBis, two evaluation boards, and one computer:

USBi #1 with ADAU1701 board

USBi #1 with ADAU1442 board

USBi #2 with ADAU1701 board

USBi #2 with ADAU1442 board

Based on those results we should more easily be able to see where the problem is coming from.

The communication protocol firmware in the USBi makes no distinction between different SigmaDSP ICs. SigmaStudio simply sends four bits of information: protocol (I2C/SPI), chip address/latch, address, data. The USBi blindly translates that into the appropriate comm protocol and sends it to the target. So, if you USBi works for one evaluation board, it should work for all evaluation boards.

I expect that there could possibly be a problem with register settings in the SigmaStudio project or switch settings on the board. Anyway, let's start with the steps I have listed above and move forward from there.

Actually, a few customers recently experienced a problem where they opened up an old project file in a newer version of SigmaStudio and a register setting had changed seemingly on its own, which caused communication errors. Please check the setting of the Start Pulse Select register on the DSP Register Modes 1 page of the register window. It's possible that this register has been set to "NONE" when you upgraded versions of the software. If so, set it back to 48kHz (or 96kHz or 192kHz, depending on your system).

Another idea is to check that R164 and R165 are populated on your ADAU1442 evaluation board. These are the 2k I2C pull-up resistors. A few boards may have been accidentally sent out without these resistors populated on the board, and this will cause I2C communication not to work.

The interesting thing is that Sigma shows 'Active downloaded' status even when USBi is not connected to any hardware,

so if you don't read anything from the hardware, there is no feedback.

Probably for i2c it's not the case, since no acknowledge will be received from the target, but we use spi,

so no acknowledge is requred.

And in our case we don't use the eval board, but working with the actual hardware, which is the same in both locations.

We will double check tomorrow that register settings match in both locations.

Ah, yes the green "download" bar actually only works in I2C mode because of the acknowledge. In SPI mode, the master - in this case, the USBi - is actually kind of blindly writing to the target. So, you'll get the green bar when the transaction is complete, whether the information actually got there or not.

In I2C, you'll actually timeout if there's no ACK from the slave. So, if you don't connect the target device, then you don't get an ACK, and therefore an error occurs after the timeout. On the other hand, if you get an ACK, then the transaction will complete itself, and the green bar appears in SigmaStudio. The green bar means: the USBi driver is installed, the USBi is attached, SigmaStudio sent the data to the USBi, the USBi sent the data out on its I2C port, and the target acknowledged.

With SPI, all the software knows is if it sent the data to the USBi or not, and if the USBi sent it out on its SPI port. You'll get a green bar in SigmaStudio, but the meaning is a little different. This time it means simply: the USBi driver is installed, the USBi is attached, SigmaStudio sent the data to the USBi, and the USBi sent the data out on its SPI port.

So, a read-back is necessary for confirming proper comms in an SPI system.

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Thank you,
EZ Admin