>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>On Behalf Of Jinx
>Sent: 11 June 2007 11:53
>To: Microcontroller discussion list - Public.
>Subject: Re: [PIC] Interfacing to a Hitachi 44780 LCD in 4-bit mode
>
>
>> Note that the LCD controller is busy for approximately 10ms after 
>> power up, so you must wait at least this long before attemping to 
>> configure it!
>
>Very true. I've had to increase my delay after power-up from 
>the usual 15ms to 30ms with some (no-name) brands. They simply 
>don't play ball if you try to initialise too early. Maybe 
>start with 50ms, decrease until it fails if power-up time is an issue

The delay needed above the 10ms minimum depends on the rise time of the power rail, and the threshold at which the PIC starts working compared to the LCD.  The original Hitachi HD44780 has a threshold of 4.5volts for the standard 5v part.  The PIC could come out of brownout as low as 3.7volts for a 5v part.

The busy flag is opertational during this period, so if you have R/W connected to a pin the safest method is to poll the busy register after power on until clear (with a suitable timeout).  I don't know if the clones do this or not.

Regards

Mike

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