Direct Digital Synthesizer Kit
Alternate LCD USE
There is a 10 pin header (2x5, 0.1 in
spacing) near the top of
the board. Full kits are shipped with my Serial LCD module.
To use this LCD simply wire straight through (Pin 1 to pin1 of the LCd
etc.) J4 jumper must be installed. The Microprocessor tests this line
at power up and will use the appropriate LCD routines depending on the
presence or absence of this jumper. If you remove the jumper,
and connect a industry standard 14 pin HD44780 LCD module it will also
work nicely. Most any LCD with at least 8 digits and a
Hitachi HD44780 or equivalent (KS0066, S6A0069) LCD
controller. An 8x2, 16x2 or 16x1 format will work, a 8x1 format
will work but only the frequency will be displayed, there's no room for
memory number etc. You can also use larger displays, i.e. 20x4 or
40x4, but the extra space is not used. My DDS board uses a 4 bit
interface to the LCD, which is a standard option with the HD44870 chip,
there are a few LCD modules out there that only have 4 bits brought out
which is fine they should work. Some LCD modules, such as the
Data Vision 16110
work but require a negative Vlcd voltage (1~2v) which you will have to
supply.
In the photo you can see an assortment on LCD modules that I have been working with. The large one at the bottom of the photo is used on my frequency counter and will be shipped with the kit. It's very inexpensive, has very large high contrast digits. The others were obtained from a variety of sources, I paid between $2 and $10 for them. Some have backlights. Some might fit inside the Altoids tin with the PCB. At this point it is unlikely I will be stocking or selling any of these other displays. Scroll down for some links to suppliers.
Expect for the tiny one on the top all of these have been tested and work. The tiny one on top is from electronics goldmine and looks promising, but has a tiny flat cable connected to it and I haven't yet have the patience to wire it up.
Note pin connection info in this table does not apply to Oct 2011 PCBs and later
They have on board connectors for various LCD types
Connecting your backlight. If your display has a LED backlight, it is usually (but not always) connected to pins 15 and 16. Normally the anode of the LED connected to pin 15, and the cathode to pin 16. In general you should connect the cathode (pin 16 ) to ground, and supply power through a dropping resistor to the anode. In some cases there is a dropping resistor on LCD module. But it's safest to start with a dropping resistor of 180 ohms or so, then adjust the value for the brightness you want. You could install a pot if you want adjustable brightness. If you need to put more than about 50mA through the backlight LED (unlikely) I would suggest you use a separate voltage source because the 5v regulator on the DDS may overheat. I you happen to have an LCD module with a CFL backlight, good luck with that, they need a high voltage power source.
VLCD Most LCD's have a separate voltage usually called VLCD, pin3 on the standard pinout. However, the voltage is not standard. Some LCD's simply require 0v (ground) on this line. Some require a negative voltage in the range of -0.5 to -1.5 volts. But most work with something in the 0 to +2.5v range, which the 1K resistor &1K pot combination generate. My serial LCD can use the 0-2.5 adjustable voltage, or simply a 10K resistor to ground works fine.
BACKLIGHTING: My personal opinion is that back lighting is overrated. LCD's can be reflective, transmissive, or transreflective. Reflective means they reflect 100% of the light coming in. Transmissive means they pass 100% of the light from behind. Transreflective LCDs are a compromise, they reflect 50% and transmit 50%. With transreflective LCD's frequently a shadow is very noticeable, one image from the backlight and one from the room light. Most of the LCDs above are transreflective. The ones with backlights are very readable when the backlight is on, barely readable when it's off. The ones without backlights have only fair contrast. The serial LCD is 100% reflective display and has excellent contrast Very readable in low room light, but not readable in the dark.
Also the LED backlights require a decent about of current. You almost always need to install a separate resistor in series with the backlight LED to limit current. In most cases 47ohms is a good choice. But this will approximately double the current draw of the DDS VFO. Please do not draw more than 50mA through the DDS PCB unless you heatsink the 7805 regulator. If you are operating portable, consider an LCD without a backlight, or put a switch in line to turn off the backlight when you don't need it.
If you happen to have an LCD modules or find one on-line that looks nice, email me the info about it and I'll see if I think it will work. If you want, you can send it to me, with a few $ for return postage, and I'll test it and return it. A LCD module with controller is needed, simple LCD glass does not work.
Sources:
All Electronics (LCD-111 Wintek C2401P will not work)
Electronics Goldmine (Low prices, small quantities, selection varies)
SHOPEIO (Great selection, some expensive, some bargains) No Longer Recomended
Ebay (search for LCD Module)
In the photo you can see an assortment on LCD modules that I have been working with. The large one at the bottom of the photo is used on my frequency counter and will be shipped with the kit. It's very inexpensive, has very large high contrast digits. The others were obtained from a variety of sources, I paid between $2 and $10 for them. Some have backlights. Some might fit inside the Altoids tin with the PCB. At this point it is unlikely I will be stocking or selling any of these other displays. Scroll down for some links to suppliers.
Expect for the tiny one on the top all of these have been tested and work. The tiny one on top is from electronics goldmine and looks promising, but has a tiny flat cable connected to it and I haven't yet have the patience to wire it up.
Note pin connection info in this table does not apply to Oct 2011 PCBs and later
They have on board connectors for various LCD types
| HD44870
Pin # |
Signal
Name |
Connect
to PCB |
| 1 |
Gnd |
2(Gnd) |
| 2 |
+5v |
1 |
| 3 |
Vlcd |
9 |
| 4 |
R/S |
5 |
| 5 |
R/W |
2(Gnd) |
| 6 |
E |
3 |
| 7 |
DB0 |
2(Gnd) |
| 8 |
DB1 |
2(Gnd) |
| 9 |
DB2 |
2(Gnd) |
| 10 |
DB3 |
2(Gnd) |
| 11 |
DB4 |
4 |
| 12 |
DB5 |
6 |
| 13 |
DB6 |
8 |
| 14 |
DB7 |
10 |
Connecting your backlight. If your display has a LED backlight, it is usually (but not always) connected to pins 15 and 16. Normally the anode of the LED connected to pin 15, and the cathode to pin 16. In general you should connect the cathode (pin 16 ) to ground, and supply power through a dropping resistor to the anode. In some cases there is a dropping resistor on LCD module. But it's safest to start with a dropping resistor of 180 ohms or so, then adjust the value for the brightness you want. You could install a pot if you want adjustable brightness. If you need to put more than about 50mA through the backlight LED (unlikely) I would suggest you use a separate voltage source because the 5v regulator on the DDS may overheat. I you happen to have an LCD module with a CFL backlight, good luck with that, they need a high voltage power source.
VLCD Most LCD's have a separate voltage usually called VLCD, pin3 on the standard pinout. However, the voltage is not standard. Some LCD's simply require 0v (ground) on this line. Some require a negative voltage in the range of -0.5 to -1.5 volts. But most work with something in the 0 to +2.5v range, which the 1K resistor &1K pot combination generate. My serial LCD can use the 0-2.5 adjustable voltage, or simply a 10K resistor to ground works fine.
| Manufacturer | Part # | Format | Type | Backlight | Backlight Resistor | Overall Dim | Cost | Min S/H | Vlcd | Comp. w/ N3ZI DDS |
Advantages | Disadvantages | Source |
| ModuleHouse | KTM-S1201 | 12x1 | Numeric | None | N/A | 4.9 x 1.3 x 0.4 | FREE | FREE | Fixed 10K to Gnd | Compatible | Large highly visible digits, low cost | too big for small radios, no text | N3ZI |
| Orient | AMC1601AR | 16x1 | Alpha | LED | 47 ohm | 3.2 x 1.4 x 0.6 | $4 | $7 | Ground | Compatible | Nice, Readable, nice backlight large Characters | Slightly Noticeable Reflection | ShopEIO |
| Electrolyte | QY-162A | 16x2 | Alpha | LED | 47 ohm | 3.2 x 1.5 x 0.6 | $4 | $4 | 1K + 1kTrim Pot | Compatible | Very Readable, Avail in different colors | Thick, Backlight not as uniform as others | Ebay/ FCB Electronics |
| JHD | JHD802A | 8x2 | Alpha | LED | 47 ohm | 1.7 x 1.4 x 0.3 | $5 | FREE | 1K + 1kTrim Pot | Compatible | Mediocre contrast, only 8 char's per line | Ebay/ szdigitalsquare | |
| SURE | DE-LM001 | 8x2 | Alpha | LED | 47 ohm | 1.7 x 1.4 x 0.6 | $6.50 | FREE | Ground | Compatible | Nice, Readable, nice backlight | Thick, only 8 char's per line | Ebay/ SureElectronics |
| Truely | MCC162C4 | 12x2 | Alpha | None | 3.3 x 1.4 x 0.3 | $4 | $7 | 1K + 1kTrim Pot | Compatible | Mediocre contrast | ShopEIO | ||
| Sharp | LM16255 | 16x2 | Alpha | None | N/A | 3.2 x 1.9 x 0.4 | $2-$5 | $7 | 1K + 1kTrim Pot | Compatible | Mediocre contrast | ShopEIO, All Electronics | |
| Seiko | C550001 | 16x2 | Alpha | LED | 22 ohm | 2.7 x 1.0 x 0.5 | $3 | $7 | -0.4 to -1.4 volts | Compatible, but needs negative voltage for LCD | Nice Compact Display | Negative Voltage needed, Thick, only fair contrast | ShopEIO |
| Datavision | 16110 | 16x1 | Alpha | None | N/A | 4.9 x 1.4 x 0.4 | $2-$5 | $7 | -0.4 to -1.4 volts | Compatible BUT Requires Negative Voltage for LCD | Very Readable without backlight | Requires Negative Voltage for LCD | Electronic Goldmine, ShopEIO |
| Shin Nichi | LCM-5016-67HR | 16x2 | Alpha | EL | N/A | 3.1 x 1.4 x 0.4 | $3 | $7 | ? | Should work, but it doesn't. No data | My sample didn't work at all | ShopEIO | |
| Hantronix | HDM16216L | 16x2 | Alpha | LED | N/A | 2.2 x 0.8 x 0.4 | $4 | $7 | ? | I'm working on it, should work, but very difficult I/O cable connector | Electronic Goldmine | ||
| Wintek | WD-C2401P | 12x1 | Alpha | None | N/A | 4.2 x 0.7 x 0.4 | $2 | $7 | None | Nope, oddball interface | Won't work | All electronics, Electronic Goldmine | |
BACKLIGHTING: My personal opinion is that back lighting is overrated. LCD's can be reflective, transmissive, or transreflective. Reflective means they reflect 100% of the light coming in. Transmissive means they pass 100% of the light from behind. Transreflective LCDs are a compromise, they reflect 50% and transmit 50%. With transreflective LCD's frequently a shadow is very noticeable, one image from the backlight and one from the room light. Most of the LCDs above are transreflective. The ones with backlights are very readable when the backlight is on, barely readable when it's off. The ones without backlights have only fair contrast. The serial LCD is 100% reflective display and has excellent contrast Very readable in low room light, but not readable in the dark.
Also the LED backlights require a decent about of current. You almost always need to install a separate resistor in series with the backlight LED to limit current. In most cases 47ohms is a good choice. But this will approximately double the current draw of the DDS VFO. Please do not draw more than 50mA through the DDS PCB unless you heatsink the 7805 regulator. If you are operating portable, consider an LCD without a backlight, or put a switch in line to turn off the backlight when you don't need it.
If you happen to have an LCD modules or find one on-line that looks nice, email me the info about it and I'll see if I think it will work. If you want, you can send it to me, with a few $ for return postage, and I'll test it and return it. A LCD module with controller is needed, simple LCD glass does not work.
Sources:
All Electronics (LCD-111 Wintek C2401P will not work)
Electronics Goldmine (Low prices, small quantities, selection varies)
SHOPEIO (Great selection, some expensive, some bargains) No Longer Recomended
Ebay (search for LCD Module)