Difference between revisions of "Reset scheme (Naon)"

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==Accessible reset signals==
 
==Accessible reset signals==
Five different signals are provided by Naon SOM. FOllowing sections describes in more detail each one.
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Five different signals are provided by Naon SOM. Following sections describe in more detail each one.
 
===MRST (J2.102)===
 
===MRST (J2.102)===
 
This pin is connected to HDRST signal (cold reset) of [http://www.ti.com/product/tps659113 PMIC TPS659113]. When high, this signals keeps PMIC in off mode and resets TPS659113 to default settings. MRST has a weak internal pulldown.
 
This pin is connected to HDRST signal (cold reset) of [http://www.ti.com/product/tps659113 PMIC TPS659113]. When high, this signals keeps PMIC in off mode and resets TPS659113 to default settings. MRST has a weak internal pulldown.
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PORSTn is a bidirectional open-drain signal. It is connected to:
 
PORSTn is a bidirectional open-drain signal. It is connected to:
 
* PORn input (Power-on Reset) of DM8148 processor
 
* PORn input (Power-on Reset) of DM8148 processor
* output of voltage monitor ([#Voltage monitor])
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* output of voltage monitor (see [[Reset scheme (Naon)#Voltage monitor]])
 
* NRESPWRON2 output of PMIC.
 
* NRESPWRON2 output of PMIC.
 
Internal pullup is 10kOhm.
 
Internal pullup is 10kOhm.
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===RSTOUTn (J2.91)===
 
===RSTOUTn (J2.91)===
 
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:
 
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
 
* RSTOUT_WD_OUTn pad of DM8148 processor
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* 2k2 pull down resistor
 
* peripherals and memories.
 
* peripherals and memories.
 
In case it is used to reset devices on carrier board, its driving capability has to be taken into account.
 
In case it is used to reset devices on carrier board, its driving capability has to be taken into account.
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==Voltage monitor==
 
==Voltage monitor==
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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.

Latest revision as of 14:43, 24 June 2013

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

Accessible reset signals[edit | edit source]

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

MRST (J2.102)[edit | edit source]

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 | edit source]

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

Internal pullup is 10kOhm.

RSTOUTn (J2.91)[edit | edit source]

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 | edit source]

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 | edit source]

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

Voltage monitor[edit | edit source]

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.