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SHARP Memory Display Booster Pack


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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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@@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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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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