chicken

SHARP Memory Display Booster Pack

98 posts in this topic

As discussed in this thread, I took a first stab at a Booster Pack for the 1.35" SHARP Memory Display.

 

As suggested by @@greeeg, I added two footprints:

  1. FPC connector (on the back)
  2. zebra strip connector (on the front)

While the outline is for the 1.35" variants (LS013B4DN01, LS013B4DN02, LS013B4DN04). The 1.28" (LS013B7DH03) and 1.26" (LS013B7DH01) displays should work too as the FPC cables are of similar length and zebra footprints are identical.

 

The smaller, circular displays might work, but the length of the FPC cable might be too short.

 

The larger displays have the same FPC cable, but will overlap with the LaunchPad connectors. I could fit the next size up (2.7", LS027B7DH01) when rotating the screen 90 degrees.

 

I only supply 3.3V. The current small-sized displays are all 3.3V. The older 1.35" versions specify 5V supply voltage, but in my experience work fine with 3.3V. I don't know about the larger displays.

 

Connections are as follows:

SCLK -> P1.5 (SPI CLK)

SI -> P1.7 (MOSI)

SCS -> P2.5 (SPI CS)

DISP -> P2.0 (display on/off)

 

I did go with the BoosterPack recommendations for SCS and DISP, but I'm considering to put them somewhere on the upper 14 pins to maintain compatibility with my original code which was for the MSP430G2231.

 

Not yet connected are EXTMODE and EXTCOMIN. These are to control how the LCD polarity-toggling is driven. If EXTMODE is high, toggling is done through EXTCOMIN, otherwise it's done through SPI. I might pull EXTMODE low with a resistor and expose jumper pads to change the configuration.

 

I filled the front plane with 3.3V and the back plane with GND.

 

The horizontal shape at right below the zebra strip pads is the cutout for the flex cable.

 

Any input is greatly appreciated.

 

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yosh likes this

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@@chicken, Thanks.

 

Not yet connected are EXTMODE and EXTCOMIN. These are to control how the LCD polarity-toggling is driven. If EXTMODE is high, toggling is done through EXTCOMIN, otherwise it's done through SPI. I might pull EXTMODE low with a resistor and expose jumper pads to change the configuration.

 

In such a case I find  general GPIOs, and connect to the pins via a solder jumper. The SDCard boosterpack has this feature and it is prejumpered when the PCB is made, so the user has to cut the trace between the jumper in case the pin needs to be used for something else. It helps keep the code synced with hardware, without any configuration to the hardware.

Just a tip.

 

Looking at the renderings, I don't see 40 pin boosterpack support. The extra header can be "dumb", but will help in stacking.

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Attached the updated version.

 

- added 2nd header rows for 40 pin booster pack support

- added solder pads for all connections

- added 3-way solder pad for selecting EXTMODE (software or hardware)

- added 3-way solder pad for 3.3V vs 5V supply voltage selection

- moved slot for FPC further down, 1st attempt got some cable lengths wrong

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yosh likes this

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Can we pre-order now based on an approx (or even unspecified) price?  I imagine a new booter like this will be popular.

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Oops.. yes. Spirilis uses diptrace, which prompted me to try it out. I like it, compared to Eagle.

@@chicken, just put 43oh text if you want. 

 

@@luke If chicken is ok with the design. I can go ahead an order it. I think at price, it will be around $3.50 shipped.

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I don't know about pre-orders,

 

I wanted to spin it via OSHPark first to verify that it actually works - but then, that will cost me twice of 10 boards from Seeed et al. Might just as well risk a small production run.

 

As for price, the cost structure is as follows:

- PCB ~5x5cm/2x2" $1

- 3 decoupling caps <$0.1

- FPC connector $1.15-$1.50

- Stackable headers $0.5?

- Display $12-$18

 

I don't know what @@bluehash has in mind. As the display is 80% of the cost, it might make more sense (less risky) to just sell the populated board without the display. However availability of the display might be an issue. Currently I can only find it at Mouser.

 

Also of note, breakout boards with display sell for $38-40.

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Yeah as a general rule I don't prefer OSHpark over Elecrow if the price difference per-board is dramatic... the main advantage OSHpark has imo is the copper seems better cemented, I think they use better stock for their boards to survive RoHS solder rework et al, it's very hard to lift pads with re-soldering 'n stuff.  I've lifted pads off Elecrow boards like they were scotch-taped.

 

But during the Chinese holiday and some short weeks after (cause they'll probably be busy with backlogs), OSHpark has the advantage.

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Some final cosmetic edits:

- added 43oh logo

- reduced width by 1mm to fit within 5cm

- nudged a few traces around for better plane fill-in

- rotated EXTMOD jumper to same orientation as the others

 

I think it's ready to go.

 

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yosh likes this

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As suggested added board name, my name and revision information.

 

Also moved EXTMOD jumper closer to EXTIN as the two are related, and some general untangling of wires.

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bluehash likes this

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PCBs look good to me.

 

Does the slot for the FPC increase the fabrication price? I've always just brought a cutout in from the edge of my boards, or is that what you're doing?

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Ordered 10 pieces at Elecrow. Probably will take a long while.

 

And an ad-hoc poll: Of those that consider buying the PCB for the $3.50 quoted by @@bluehash, who would prefer to have the FPC connector included (not soldered!) for an additional $1.20? (I will go with the majority decision)

 

@@greeeg At least at OSH Park, inside cutouts can be drawn on the board outline layer. No extra cost.

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The boards arrived and they look great, wonderful job by Elecrow!

post-9974-0-81081200-1394321146_thumb.jpg

 

Mounting the display with the FPC through the cutout is a bit fiddly, but other than that everything worked out as planned.

 

I ported my old memory display code to the 2553 and everything worked fine, until I sticky-taped down the display and arranged it to take the picture, when the magic smoke escaped. Literally! With a sizzling sound :sad:

 

post-9974-0-50682100-1394321545_thumb.jpg

 

Either it was dirty contacts (the display contacts had a bit of green oxidation after having spent a year in the junk drawer), or I shorted contacts by yanking too hard on the cable when applying the sticky tape.

 

Anyways, looks like I will have to order a new one.

bluehash likes this

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@@chicken Those boards do look great. Such a shame about your display :(

 

Having that cutout come all the way to the edge of that PCB may have made inserting the FPC easier, but it would be more exposed. 

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Success!

 

post-9974-0-91498200-1394849580_thumb.jpg

 

The new display (LS013B4DN04) arrived in the mail today and after wasting a connector on the first board, just to find out that I also burned out a trace, the 2nd attempt did work without smoke and sizzling noises. Good thing Elecrow sent me 11 PCBs :smile:

 

Will coordinate with @@bluehash to get the remaining 9 PCBs (incl. matching FPC connector) into the store.

dubnet, pine, bluehash and 2 others like this

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