blackfin bf537 custom board .ldf questions

[EricP]

Hello All:

 I have designed a custom board for the BF537.  I am connecting to it using the USB JTAG emulator from Analog Devices.  I am able to connect to the board in VisualDSP and program it with example code (one turns on the SPI, another echos what is received on the UART)  Everything seems to work fine in VisualDSP.  The problems I am having are when I try to load LabVIEW .dxe files.  I built a simple UART echo program that runs fine when I am connected to the EZ-KIT board but does not work when connected to my custom board.  I have been able to get the UART to transmit data on the custom board but not receive data.  Again, everything works fine if I am using VisualDSP .c files.  I have been reading that I need to modify the .ldf file, however my custom board uses the same type of memory configuration as the EZ-KIT.  I talked to a guy at analog and he said the .ldf file should be fine as it is because the memory is the same.  Can anyone provide some insight into this one, is it necessary to edit the .ldf?  I dont think this is a hardware issue as everything works fine using VisualDSP project files.

Thanks,

Eric

[Kevin_S]

Hi Eric,

On the BF537 ZE-KIT board, there is only one UART connector (UART 0, I believe).  The BF537 has two UART ports though.  Did you break out the UART 0 (or UART 1) port to the connector on your custom PCB?

Are you able to successfully download your code from LabVIEW?  (The problem is that the downloaded code just doesn't fully utilize the functionality of your UART, correct?)

Are you able to successfully use a different LabVIEW program on your custom PCB?  (A shipping example, perhaps?)

Kevin S.

Applications Engineer

National Instruments

[EricP]

the problem was with the RTC, it wasn't powered correctly.  It seems that there are timing functions in labview that utilize the RTC that may not necessarily be used in VDSP.  I am seeing an occasional 90 degree phase shift on my rtc signal, is this going to cause problems?

Message Edited by EricP on 07-24-2009 04:02 PM

[Kevin_S]

Hi EricP,

I wouldn't be surprised at all if the RTC is needed by the VDK embedded operating system running on the Blackfin.  In LabVIEW, you even have access to the RTC through VIs.

I'm curious as to how you're seeing an occasional 90 degree phase shift in the RTC.  Can you specifically cause the clock phase to change, or does it happen randomly?  (This might be a good hardware question for Analog Devices.)  Regardless, I haven't specifically monitored the RTC line with an oscilloscope in an attempt to monitor phase.  I'm also curious as to whether or not this affects your running code.  Have you seen instances where your code will and won't run correctly due to this RTC phase shift?

Kevin S.

Applications Engineer

National Instruments

[EricP]

The phase shift appears randomly on my board, I probed the signal on the EZ-KIT board and I am not seeing any phase shifts.  My program is having difficulties running, it works for up to 30 seconds at most and then "crashes".  I can watch the current draw of my board from my power supply, when the board is running normally it pulls around 310 mA, when the program is about to crash it starts to drop and then "idles" at 150 mA.  Watching on the oscope, the power signal starts to get dirty and the voltage fluctuates right before the crash.  I haven't been able to determine if the RTC is creating this problem or if a problem with the power supply is the cause.

[Kevin_S]

Hi Eric,

I've been doing some reading on the RTC for the BF537.  (See page 23 of 68 in this pdf.)  It appears that the voltage supply needed for it is between 2.25V and 3.6V.  Are you providing this?  (How was it hooked up previously when you mentioned that it wasn't powered correctly?)

Does the crash only happen with programs downloaded from LabVIEW?  Or do all of your programs crash (those downloaded through LabVIEW and the VDSP environment)?

I can try to help a little concerning RTC functionality on the board, but I am not an expert by any means.  If you are diving deeper into the RTC functionality and how it may be used by the services (the LabVIEW calls into) on the Blackfin, you might want to specifically contact Analog Devices.

Kevin S.

Applications Engineer

National Instruments

Message Edited by Kevin_S on 07-28-2009 05:01 PM

[EricP · Accepted solution]

I got it fixed, there was a problem with the voltage regulators providing stable output.