Figure 2-8 shows the reset architecture of the AM275x EVM.
The AM275x SoC has the following
resets:
- MCU_PORz is the
Power-On-Reset for the AM275 SoC.
- MCU_RESETz is the Warm Reset
to AM275 SoC.
- RESETSTATz_1V8 is the reset
status output for the Main Domain.
Figure 2-9 MCU_PORz Reset Signal
Tree
The MCU_PORz signal is driven by a
3-input AND gates that generates a power on reset to the SoC when:
- The PMIC drives the PMIC
PowerGood output signal low.
- The 5V buck regulator outputs
a low signal for the power good signal.
- An external JTAG debugger
drives the JTAG emulation reset signal low.
- The XDS Test Automation
Header outputs a logic LOW signal (TEST_MCU_PORzn).
- The user push button (SW8) is
pressed.
The MCU_PORz signal is tied to:
- AM275x SoC PORz input
- Audio Expansion Connectors (1
and 2)
MCU_PORz is also driven LOW by
populating Jumper J32, thus shorting MCU_PORz to ground.
The MCU_RESETz signal creates a warm
reset to the SoC when:
- The user push button (SW6) is
pressed.
- The Test Automation Header outputs a logic LOW signal (TEST_WARMRESETn) to a
P-Channel MOSFET gate that causes V_GS of the PMOS to be less than zero and
so the MCU_RESETz signal connects to the PMOS drain that is tied directly to
ground.
The MCU_RESETz signal is tied to:
- AM275x SoC MCU_RESETz
input
The RESETSTATz_1V8 signal is the reset
status signal for when a power-on reset or warm reset is triggered
The RESETSTATz_1V8 signal is tied
to:
- Ethernet Expansion Connector
reset (1 and 2)
- IO expander(U18) reset
- HYPERRAM reset
- OSPI reset
- eMMC reset
- MMC0 SD enable
- PCM reset (1 and 2)
- Audio Expansion Connector (1
and 2)
- BOOTMODE buffer output
enable
The AM275x EVM has two dedicated
external interrupts to the SoC:
- GPIO1_23_INTn, that occurs
when:
- The user push button
(SW5) is pressed.
- The Test Automation
Header outputs a logic LOW signal (TEST_GPIO1) to a P-Channel MOSFET
gate that causes V_GS of the PMOS to be less than zero and so the
GPIO1_23_INTn signal connects to the PMOS drain that is tied directly to
ground.
- PMIC generated Interrupt output
is tied to either:
- GPIO1_29 of the AM275x
SoC
- EXTINTn of the AM275x
SoC
- Both Ethernet Add-on
connectors