November 2, 2011
about 3 years ago
Since still can be googled, that this display wouldn’t be worth the few bucks it costs due to the problems, some folks had with it:
I have now more than a hand full of them all working seemlessly, following the four simple rules for that cheap but price-worthy display:
A) feed them from sufficiantly “stiff” power source (Low ESR 100µF in 5 V output)
B) Add a sender-side pullup resistor to 3,3 V for the Rx line.
C) Add a procedure on the controlling mic, in which the user holds a button down during startup, if the display eventually lost its baud rate setting displaying any shit but no chars.
Start from 2400 Baud, set the LCD Baudrate to your standard one.
End up talking with 38600 Baud to the display, setting your standard baud rate.
Any time the customer has a messed-up display, he repowers the display holding down that start-up-Button, and:
LCD is displaying properly again…
To me, this display really is competitive to others of nearly the same specs, coming from Canada for double the price.
It is really good readible in full sunlight and with low power consumption led backlicht also in the complete darkness.
My wish to sparkfun:
Make the contrast adjusteable via serial command, not by potentiometer…!!!!!
Really serious wish: Buying a lot in future, if that maybe possible.
I first had problems using this serial 20x4 LCD module via software serial (bitbanging). It is controlled from a Leaflabs Maple Cortex M3 processor, which output pins are turned to floating state during flashing. Really ennoying in development phase: Hundreds of random chars appeared on the display, changing the baud rate, changing the setup as 20x4…
Cure: External 10kOhm Pullup resitor on the TX-line to 5 Volts. (Use a 5 V tolerant pin on the maple for the serial communication to the LCD.
Now: Flashing the MIC, resetting - without any problems with this LCD.
Criticism: such pullup could have been implemented in the LCD design. Designed as a Voltage divider to meet the 3,3 V TTL specifications of most Controllers around.
Further: Where is a reset Pin for the PIC driving the LCD? Bad Documentation.
No public wish lists :(
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