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The capacitor values are:
[CODE]
Pin Left side Right side
6 100 nF 2n2 F
7 100 nF 100 nF
8 1 uF none
[/CODE]
As mentioned in the text, the capacitors on pins 6 and 7 are more for noise filtering and I have experimented successfully with 100 nF to both pins and no cap on these pins (but still a tantalum cap on the output of the 3V3 voltage regulator.
I have also found another datasheet for an Philips OM6208 96x65 gLCD driver chip.
Almost the same as the PCF8814 but whereare the PCF8814 is monochrome (1-bit resolution) as are the 1100 and 2280 displays, the OM6208 is 4 levels of grey scale.
With the Nokia 2280 gLCD I have again tried the BRS command and it is working.
The top 4 blocks of 8 lines (32 pixels high) are swapped with the lower 4 full blocks (32 pixels) but also inverted at the same time.
So if we add in the two extra subroutines:
[CODE]NoBRS:
Value = $E0 ; normal display with dark chars on light background
GOSUB CommandToLCD
RETURN
;----------------------------------------------------
BRSOn:
Value = $E1 ; normal display with dark chars on light background
GOSUB CommandToLCD
RETURN
;----------------------------------------------------[/CODE]
And then call two subroutines:
[CODE] GOSUB BRSOn
GOSUB VertMirror[/CODE]
then in terms of text, the top 4 rows of 8 pixel high characters are swapped with the lower 4 rows of characters and they are correctly orientated to be read.
In character line format the standard/normal presentation:
[INDENT]
Pixel row 0
Pixel row 1
Pixel row 2
Pixel row 3
Pixel row 4
Pixel row 5
:
:
:
Pixel row 61
Pixel row 62
Pixel row 63
Pixel row 64 [/INDENT]
becomes
[INDENT]
Pixel row 32
Pixel row 33
Pixel row 34
Pixel row 35
Pixel row 36
Pixel row 37
Pixel row 38
:
:
Pixel row 64
Pixel row 65
:
:
Pixel row 0
Pixel row 1
Pixel row 2
Pixel row 3
Pixel row 4
Pixel row 5
:
:
Pixel row 30
Pixel row 31
Pixel row 32[/INDENT]
Will have to go back and recheck this functionality on the Nokia 1100 gLCD as first attempts did not see any change using the "BRS" command/function.
Unfortunately the above does not quite line up with our usual 8-pixel high character rows.
If you think of it in terms of character lines the first line is pushed down 4 lines but as there are 65 rows of pixels, the top rown form the next line is placed in the very bottom pixel row with the rest of the display rolling over and continuing at the top of the gLCD display.
EDIT:
Have rechecked the Nokia 1100 and the BRS feature definitely does not function with the Nokia 1100 as had previously been identified but does work as described above for the Nokia 2280.
Last night I assembled a PICAXE to Nokia 1100 gLCD interface circuit on a prototyping board.
I tried a 1/2 sized Gadget Gangster board which was large enough but did involve a few more links compared to the proto boards I usually use due to absence of traces for a double power supply bus around the board.
Compared to the bread-boarded version, I elected to run the backlight LEDs direct form the 5 Volt supply which reduces the current through the LP2950 3.0 Volt regulator.
This also necessitated using two transistors as opposed to the original one transistor for the backlight driver circuit.
I have updated the parts 2 and 3 of the demo/basic tutorial on page 1 of this thread to reflect the changes including the embedded schematic diagram.
I have used a 150 Ohm resistor in series with the gLCD backlight LED pad connection. This limits the current to around 18 mA which is about as low as the current can go for the display to be readable in the dark.
Next I will mount the interface into a plastic box using my usual DA-15 plug type connector for further experiments via my main PICAXE Experimenters box.
Considering the Nokia 1100 schematic show a 4.7 Ohm series resistor for a ~3V supply (and the Nokia 1100 circuit does not have a PWM chip as the Nokia 2280 does), this equates to a current of 144 mA. So albeit without a datasheet for the backlight LED’s there is seemingly some capability for greater LED current.
Attached to this post are:
1. the layout produced with PEBBLE for the circuit I used, based upon the Gadget Gangster ½-sized prototyping board, and
2. A photo of the interface board and the gLCD module prior to mounting the interface into a plastic box.
For the gLCD, I have also retained and mounted the clear protective screen from the original Nokia case in front of the LCD and mounted the entire gLCD assembly using some of the Nokia screws and a 3mm long nylon spacer at each corner of the display.
To close off on the Nokia 1100 and 2280 gLCD modules, attached are:
1. A PICAXE to Nokia 2280 gLCD interface schematic which takes into account the need for the 1 uF capacitor on pin 8 of the gLCD and separate drive for the backlight LEDs if salvaged from the original PCB.
2. A PICAXE demo program to show the BRS (Bottom Row Swap) and driving the backlights for the 2280 based gLCD
(Had to provide as an attachment due to text length if embedded in the post).