Post by thread:[PIC]-Nokia 3310 LCD interfacing problems?

part 1 842 bytes content-type:text/plain; (decoded base64) We are using the Nokia 3310 Lcd (PCD8544 - controller) in a project . The 3310's operating voltage is 2.7V to 3.3V. at the moment we are using a PIC16F877 (not the low voltage variant) in conjunction with two ULN2803 drivers( to invert the signal two times ), in order to convert the signal from the PIC to a lower voltage (3V level) required by the 3310. We are having problems with the logic levels. Can we connect the 3310 directly to the PIC's 5V outputs, or will the 3310 be damaged? Are there other interfacing chips that we can use? Thank you for the help. NOTICE: Please note that this eMail, and the contents thereof, is subject to the standard P E Technikon eMail disclaimer which may be found at: > part 2 79 bytes content-type:text/plain; charset="us-ascii" (decoded 7bit) ____________________________________________

On Nov 8, 2004, at 12:08 AM, Odendaal Morne wrote: > at the moment we are using a PIC16F877 (not the low voltage variant) > in conjunction with two ULN2803 drivers( to invert the signal two > times ), > in order to convert the signal from the PIC to a lower voltage (3V > level) > required by the 3310. The ULN2803 is a high current darlington driver. It doesn't source current, and the darlington has a significant voltage drop (though perhaps not at the low current levels needed to drive signals lines.) It doesn't seem surprising to me that you'd be having problems using them as level converters. Many low-voltage capable logic families are tolerant of 5V at their inputs, and could potentially be used as level translators. TI's "Selecting the Right Level Translation Solution" ( http://www-s.ti.com/sc/psheets/scea035a/scea035a.pdf) says: "Devices from the AUC, LVC, LV-A, and AHC families have overvoltage-tolerant inputs." BillW ____________________________________________

Odendaal Morne wrote : > We are using the Nokia 3310 Lcd (PCD8544 - controller) in a project . Hi. Here is a page that uses a similar controller (PCF8558) : http://www.xs4all.nl/~lous/i2c_lcd/lph_i2c.htm A lot of the stuff about supply voltages might not apply, but the 5V -> 3V interfaces could be general in nature. It's just a voltage divider using two resistors. 3V -> 5V interfacing needs a bit more, but you didn't mentioned that you had to do that anyway... Jan-Erik. ____________________________________________