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Reset scheme (Naon)

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Naon am387x-dm814x.png Applies to Naon
Dido-main.png Applies to Dido

Contents

Accessible reset signalsEdit

Five different signals are provided by Naon SOM. Following sections describe in more detail each one.

MRST (J2.102)Edit

This pin is connected to HDRST signal (cold reset) of PMIC TPS659113. When high, this signals keeps PMIC in off mode and resets TPS659113 to default settings. MRST has a weak internal pulldown.

PORSTn (J2.109)Edit

PORSTn is a bidirectional open-drain signal. It is connected to:

Internal pullup is 10kOhm.

RSTOUTn (J2.91)Edit

This ouput signal is asserted by DM8148 processor until it gets out of reset. It is usually used to reset external memories and peripherals conneteced to processor. It is connected to:

  • RSTOUT_WD_OUTn pad of DM8148 processor
  • 2k2 pull down resistor
  • peripherals and memories.

In case it is used to reset devices on carrier board, its driving capability has to be taken into account.

CPU_RESETn (J2.15)Edit

This input signal acts as External Warm Reset. It is connected to processor's RESETn pad. Internal pullup is 2.2kOhm.

JTAG_TRSTn (J2.100)Edit

This input signal acts as Emulation Warm Reset. It is connected to processor's TRSTn pad. Internal pulldown is 4.7kOhm

Voltage monitorEdit

Naon SOM is equipped with a multiple-input voltage monitor whose reset output is connected to PORSTn. Monitored voltage rails include 3.3V provided by carrier board.