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is there any conflict with the pins used by the on-chip Rom code at boot time?

 I am using AM3358zcz and running the on-chip ROM code. sysboot[4:0] is 00001b .
in my design board,
pin_A17 is used as I2C2_SDA
pin_B17 is used as I2C2_SCL
Pin_G17 is used as UART2_RXD
pin_G18 is used as UART2_TXD,
pin_A13 is used as I2S_BCLK,
pin_B13 is used as I2S_WCLK,
pin_D12 is used as I2S_TXD,
pin_D13 is used as I2S_RXD.

is there any conflict with the pins used by the on-chip Rom code at boot time? I can see the pin A17 has been used as SPI0_CLK as output.

aslo is it possible I can get the source code of the ROM code ?

  • Hi Jason,
     
    No the ROM code source is not publicly available. As for pins used, you have selected UART0 > XIP w/ WAIT (MUX2) > MMC0 > SPI0 as your boot sequence.
     
    UART0 uses pins E15, E16.
    XIP w/ WAIT (MUX2) uses pins V6, R7, T7, T6, U6, T17, U7, V7, T11, U12, T12, R12, V13, U13, R8, T8, U8, V8, R9, T9, U10, T10, R1, R2, R3, R4, T1, T2, T3, T4, R5, U5, V5, R6.
    MMC0 uses pins G17, G18, G16, G15, F18, F17.
    SPI0 uses pins A16, B17, B16, A17.
     
    The highlighted ones will cause potential conflicts with your other intended functions.
  • Thanks, Does the conflict just affect functions , not caused some damage for the pins? becuase I just using UART0 function,don't care others, once the u-boot running I will re-config the pin mux to eable all the functions for my target.

  • What you have to check is the following: if the boot sequence for some reason skips UART0, which is your first boot device, it will try the others in sequence, and a conflict may occur with an external device connected to these pins. Please check the Note in the middle of page 4064 in the AM335X TRM.