LPC1347 - Help with Invoke ISP from user code (autoisp)

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by BPC on Wed Jan 23 09:31:15 MST 2013
Hello Everyone,

I am migrating from the LPC1343 to the LPC1347.  Everything has been smooth so far, but I ran into a snag in implementing "Auto ISP" or ISP from user code using command 57.  I have taken the LPC1343 example, and based on the User Manual for the LPC1347, it appears these function should be cross compatible.  Below is the function I am using.

[COLOR=blue]/* This data must be global so it is not read from the stack */
typedef void (*IAP)(uint32_t [], uint32_t []);
IAP iap_entry = (IAP)0x1fff1ff1;
uint32_t command[5], result[4];[/COLOR]
[COLOR=blue]void ReinvokeISP(void)
  /* make sure USB clock is turned on before calling ISP */
  /* make sure 32-bit Timer 1 is turned on before calling ISP */
  /* make sure GPIO clock is turned on before calling ISP */
  /* make sure IO configuration clock is turned on before calling ISP */
  /* make sure AHB clock divider is 1:1 */
[COLOR=blue]  /* Send Reinvoke ISP command to ISP entry point*/
  command[0] = 57;[/COLOR]
[COLOR=blue]  /* Set stack pointer to ROM value (reset default) This must be the last
     piece of code executed before calling ISP, because most C expressions
     and function returns will fail after the stack pointer is changed. */
  __set_MSP(*((uint32_t *)0x1FFF0000)); /* inline asm function */[/COLOR]
[COLOR=blue]  /* Enter ISP. We call "iap_entry" to enter ISP because the ISP entry is done
     through the same command interface as IAP. */
  iap_entry(command, result);
  // Not supposed to come back!

Prior to calling this function, I disable the SYSTICK timer and interrupt.

Once iap_entry is executed, "nothing" happens, except the debugger "disconnects" as it should.  I cannot get the Mass Storage Device to pop up on my computer as it did with the LPC1343.  I have the "Soft USB Connection" circuit implemented on my board with an LED to show if the USB is connected, once iap_entry is executed, this LED turns off (as it should), but never turns back on.

I have tried doing a soft disconnect using pUsbApi->hw->Connect(hUsb, 0); prior to calling ReinvokeISP();.  I also tried a USB reset pUsbApi->hw->Reset(hUsb); prior to calling ReinvokeISP();.

Any help would be much appreciated.

Thank you.