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MCU dynamic boot control for AM335x with control of selection boot source

igx
Prodigy 30 points

I need MCU dynamic boot control for AM335x with control of selection boot source instead of a static selection of boot source with pull-up/pull-down resistors.
How to do it correctly? Do I need resistors? Or can I directly output a high or low signal from MCU pins to the boot pins of AM335x, and then I must make pins of MCU as inputs or third state after loading of AM335x? I need right solution for this problem.

  • 0
    TI__Guru**** 393215 points
    Hi,
     
    This could be done, but there are several things to consider:
    1. 1. Only some boot pins would need to be changed dynamically. Please check Table 26-7 in the AM335X Technical Reference Manual Rev.I.
    2. SYSBOOOT[15:0] value is latched on LCD_DATA[15:0] pins at PWRONRSTn release time. These pins are in High-Z state at reset release. If they are used for driving signals in the design, the SYSBOOT driving source will need to be tristated before the pins are configured as outputs.
    3. All these pins are on the VDDSHV6 power rail. They are not fail-safe, so no voltage should be applied to them before the VDDSHV6 voltage has ramped up, or after it has ramped down.