AnsweredAssumed Answered

stm32f7 FMC async trouble

Question asked by Mike Rosing on Dec 9, 2017
Latest reply on Dec 9, 2017 by Mike Rosing

I have set up the FMC with the following:

  /* Initialize the SRAM controller */

  RCC->AHB3ENR |= 1;  // turn on FMC
  FMC_Bank1->BTCR[0] = 0X00001081;
  FMC_Bank1->BTCR[1] = 0X00070607;

/*  initialize FMC I/O bus  */

  RCC->AHB1ENR |= 0X78;  //    turn on D, E, F and G
  GPIOD->MODER =  0xa000080a;
  GPIOD->AFR[0] = 0x00c000cc;
  GPIOD->AFR[1] = 0xcc000000;
  GPIOE->MODER =  0x002a8000;
  GPIOE->AFR[0] = 0xc0000000;
  GPIOE->AFR[1] = 0x00000ccc;
  GPIOF->MODER =  0xaa000aaa;
  GPIOF->AFR[0] = 0x00cccccc;
  GPIOF->AFR[1] = 0xcccc0000;
  GPIOG->MODER =  0x0000002a;
  GPIOG->AFR[0] = 0x00000ccc;


I am only using the NWE signal to latch data into an FPGA.  The bus speed is slow, with 21 clocks per transaction.  When it sends data, the timing looks ok.  The problem is there is no data transmitted until the address gets into the range of 0xa00.  The data on the data bus seems ok because sending 0x69 shows up on the data bus correctly when viewed on a 'scope.


I tried turning off the FIFO, but it did not make any difference.  The address bus is firing, but no data comes out for addresses below a certain point.  Since data does come out, the FMC seems to be set up correctly - but why is there no data below a certain point?