lpc1769 pin state during reset/turning the power on/off

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lpc1769 pin state during reset/turning the power on/off

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by dragilla on Fri Jan 13 01:23:02 MST 2012
Hi,

What is the state of gpio (and other) pins during reset and during turning the device on and off on lpc1769? (lpcxpresso1769)?

I tried to find this information in the UM but I couldn't see it in Chapter 9 and I don't know what term to search... power-on state gives me nothing.

I want to drive an enable input of other device and it's crucial for me that this device stays DISabled until I initialize some stuff in my software.

Thanks,
--
Luke
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by NXP_USA on Fri Jan 13 10:23:00 MST 2012
The pins on nearly all NXP LPC MCUs are configured as GPIO inputs with a weak pullup. You can add a stronger external pull down to override. Special purpose pins (crystal, USB, etc) may vary but you probably won't be using those as an enable pin.
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by Polux rsv on Fri Jan 13 04:07:37 MST 2012
In the UM, chapter 8, check the PINSEL and PINMODE registers. The values at reset are explainend and you could check if the configuration is ok for your application.
In the microcontroller world, usualy, an I/O is set as an input, sometimes with a pull-up activated. But check everything, as some dedicated pins are input only, or output only.

Angelo
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