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Forum Index : Microcontroller and PC projects : PIC32MX470 PCB
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bigmik Guru  Joined: 20/06/2011 Location: AustraliaPosts: 2870 |
Hi All, I am considering doing a 470 based LCD `backpack' board. I am just wondering how many different pinouts might be out there for these Display panels.. There is the 14pin (SIL) that the 2.4"/2.8" SPI displays use There is the 40pin (DIL) that some/most Parallel TFTs use There is the 26pin (DIL) that I have seen on some RPi boards (no info yet on these) There is the 34pin (DIL) That I have on a 3.2" module I have. And there are those smaller (10pin) modules although I figure that a `backpack' board mounted on a tiny module might not be practical. I am tossing up the idea of supporting the 14pin interface (maybe jumper optioned to accommodate the 10pin as well) and the 40pin interface.. Are all the 40pin interfaces compatible with each other? Are there any other ideas that might be good to include besides the uSD socket (although I am thinking of a jumper interface to use the socket on --- some of -- these displays for that)? Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
MOST of the 40-pin parallel interface LCD's are pin-for-pin compatible, but it is only to be expected that some of them won't be. Although, so far, I have not found any parallel ones that don't use the exact same pinout and 40-pin header. The 100-pin MM+ PCB which is in conceptual stage at the moment, will be designed to piggy-back onto a 5" LCD using this same 40-pin parallel interface, but could also be plugged into 7" displays too. At this stage, I have no plans to design a SPI backpack board. Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Hi Mick, Bearing in mind of Geoff's/Grogs future piggy-back module (for 40pin), is it not worth focussing on the vast array of SPI TFTs? IMHO a neat solution would be to design a TFT (SPI) Backpack PCB which allows you to plug in the existing Explore64 Module. On your PCB add: 1> a FT231 chip to give serial console (USB console is a pain to use as you need to re-establish connection every time you reset the MM+) 2> a uSD socket (jumper like you say in case there is one on any attached TFT module 3> a PS2 socket WW By the way, I can confirm that 40-pin parallel connectors are NOT standardised! 
For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2870 |
Hi Grogs, WW, I wasnt aware that the 100 pinner was going to be released as a backpack but that seems logical to me, hence my thought of having exactly that on a 64 pinnner.. In fact I suspect the 64 pin unit might become obsolete unless I am missing something.. I am not keen on a board that the e64 plugs into mainly because I don't like the long simm shaped modules, although I can see the beauty as breadboard units... (I have totally lost faith in breadboards at the moment, although I have some e64 coming and intend to play with them). What I was looking at was trying to get a MuP Ver 3. based on the 64pinner up and going... It is just in the fog of my brain at this stage.. Ideally I want it to be 50mm square but that might be difficult to achieve with all that I am thinking of adding, esp the 40 pin header, but I have some tricks hiding in the `fog' I wish to try there.. I think a 14pin SPI header and a 40pin Parallel header (using the pinouts in Geoff's advanced manual) are probably the go but I want to feel the water to see if there are other options I should try to adapt.. Then there is the problem of headers for the 64pins how to group/layout these?? I see the possibility of pre-made header cables but I need to try to group these appropriately if that is the way I go. @WW, I see the problem of the USB when its built in but is that a huge deal? Doesnt that just mean you have to exit and restart tera-term etc? Is there other problems with the onboard USB? Possible addition of a MuP-TTL header to accommodate that possibilty.. Anyway Thank you for your thoughts I will add them to the fog and see if a good night sleep clears the fog a bit. (after I talk to Mr Johnnie Walker for a while when I get home from work). I am starting to feel a 64 pinner is NOT the way to go in the long term.. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8583 |
I've been doing quite a lot of thinking in this area as well. My view FWIW is that a 40-pin backpack (A 14-pin header should also be included at the opposite end of the board) should be based on the 100-pin chip. I would then connect PortE pins 0-7 to DB0-DB7 as per Geoff's usage of pins for the SSD1963. You can then connect PortA pins 0-7 to DB8-DB15. Then don't use the remaining PortA or PortE pins (there are an additional 4 portA and 2 portE pins on the 100-pin chip, portA is absent on the 64-pin chip and there is no other available 8-bit bus). This allows 16-bit transfers to a display such as the SSD1289 to be done with just 2 instructions. Other pins to the 40-pin header and 14-pin header would be as per Geoff's current allocation or other appropriate pins for things like T_IRQ. I would connect a USB type A connector (host) to the Micromite USB pins as Geoff has said he is going to add USB host functionality like Keyboard support. For the reasons stated above I personally will never use a direct connect USB console. The USB console can be provided by either the FT231 chip or PIC16F1455 connected to the standard console serial pins. I wouldn't include a PS2 port. This is outdated technology and the USB keyboard support is far more useful. There should be an onboard SDcard socket (Full size or micro?). The ones on the displays are invariably in positions that make them unusable if the display is mounted in a box. I would include a header for a DS3231 RTC module. They are so cheap it isn't worth soldering the chips, battery etc. to the backpack. I'm assuming that the display(s) headers will mount to the back of the board. I would then include an Arduino UNO header layout on the front of the board. This will include the i2c1 pins, SPI1 pins, and one of the serial ports. Other pins can be selected to meet the Arduino layout (analogue pins in the correct place) and make available as many other special function pins as possible. This allows very easy expandability. The power supply is an interesting issue. Some of the SSD1963 displays have a 5V input between the LED and REST pins, others require backlight power to be sourced from the 3.3V pin. Given the "hunger" of the 5" and especially the 7" displays, this means the power supply must be capable of providing nearly an amp at either 3.3 or 5V. My view is that a two stage power supply is needed with a switching regulator such as the LM2596 as the first stage. It may be that the cheapest way to do this is to layout the board to attach a ready built module such as this. The second stage will be a 5V-3.3V LDO linear regulator which must be specified for 1A and have heatsinking capable of dealing with 1.7W Unfortunately the layout of the board won't fit in either a 5cmx5cm or 5cmx10cm size (a 40 pin header is 51mm long and the outer pins are on 48.26mm centres) so it will need the 10cmx10cm option from most PCB vendors (this size is currently only USD1.90 each from Itead at 10-off quantities). No board is going to meet all requirements, but something based on the above (given the Arduuino header) would solve everything I can envisage at the moment. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
The conceptual idea for the 100 pin unit that plugs directly into a 5" LCD, would have a PCB size the same as that 5" LCD - about 133mm x 84mm or so. These boards would be more expensive to have made then the ones that stick to the more universal 50x50 or 100x100, but not by that drastic an amount - C'est La Vie..... All these LCD's built-in SD card socket can be made use of, but the problem is you have to have a custom case built(or make one yourself), with a slot to allow the card to pass through the wall of the case and engage in the socket - this is a fiddly and tricky procedure to do neatly, and laser-cutting is probably the way to go here, and is what I am looking at for my 7" LCD project. Those built-in SD sockets are also cheap friction-only ones, and have no card-detect or write-protect sensor switches, so my preference is still for a "Proper" card holder on the main PCB, and ignore the one built into most LCD modules. ...but then, that is just me... Smoke makes things work. When the smoke gets out, it stops! |
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| bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2870 |
GDay Lads, @Peter, I agree the 100 pinner is the better choice but I do not want to step on Geoff's or Grogs toes and design something that is essentially the same abd as I am not `in the loop' as to what the design of the 100pin would look like electrically I can only guess the pins used.. Bottom line is it is Geoff's project and he obviously has something planned that looks the way I see the project working. The 64pin backpack, however, is a unique idea I can use without worry of duplication.. The 5V source I am looking at is using a 2A-3A 5V switchmode plugpack as is readily available going into a 2.1mm power jack and using the inbuilt switch to disconnect USB power when the plugpack is installed. Re. The PS2 port, I was thinking of a USB connector with jumper options to be USB/OTG or PS2 (in USB format) The RTC module is the way I was going to go.. The DS3232 chip whilst easy to implement is expensive.. My intention was a 40pin at one end and a 14pin at the other for the two types of display, the 40pin will be difficult on 50mm sq admittedly, I need to consider that one carefully. Arduino header is interesting but has never seemed to take off with the `mite IMHO. @Grogs, The PCB price would rise considerably for a larger board than the prototype service that supplies the 50mm and 100mm panels.. but if you get sufficient QTY it isnt too bad.. I never get a batch done more than 50 PCBs these days (except the tiny boards of course that I can panelise.. I hear your warning on SD card and is a fair one and should be considered.. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
Something that needs consideration at this point is the fact that the 100 pin MM+ does not exist at all yet, so at the risk of jumping ahead of ourselves too much, perhaps we need to just touch the brake pedal a little and wait till Geoff gets back and we squish any bugs that are reported with the 64's while he is on Holiday? This is not to suggest that the 100 pin unit won't come to be a reality - it will, but there could be unforseen complications perhaps, in porting the MM+ 64 codebase to the 100's. One would expect not, but you know what assumptions are the mother of all....  That, and Geoff has already mentioned that you CANNOT load the 64 HEX into the 100 chip.Smoke makes things work. When the smoke gets out, it stops! |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3165 |
Mick, don't worry about stepping on my toes. My current plan is for a series of Silicon Chip articles introducing the MM+ and based on Grog's Explore 64 board and a yet to be designed backpack board for the 5" SSD1963 LCD panel. The latter will have a 40 pin connector for the SSD1963/touch/SDcard interface and probably a 100 pin chip. Other features that I am hoping will be in it include an Arduino or Click Module interface for add on boards, a real time clock chip, USB and a PS2 keyboard connector. Power supply will probably be from a 5V plugpack or micro USB connector. There is plenty of room for other boards and anyway the board that I described above will really be for the magazine readers, although hopefully TBS followers will also like it. While I am talking about future plans I should also mention that I am planning an article describing the 28-pin Micromite mounted on a LCD backback board designed to suit a 2.4" or 2.8" ILI9341 based LCD panel. It will be different from yours with the focus on a low cost and a simple design for easy construction. Geoff Geoff Graham - http://geoffg.net |
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centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320 |
Hi all This is all getting very exciting with the various options in the pipeline. Im with Bigmick I don't like breadboards but Matherps and GeoffG idea of using the Arduino pin layout is good. There are a number of prototype boards that plug into the Arduino pin layout some even have screw terminals to make connection easy. To be able to use the 50x100 size for the cheapest PCB how about placing the 40 pin connector for the 5inch LCD on one of the long sides with the SD card and usb connector etc on the opposite long side. The LCD can be connected by a ribbon cable the 14 pin connector a bit more of a problem but not insurmountable. All this would allow easy mounting of both the board and the display. I have a 100 pin 470 but I would not have a hope of soldering it. Who ever comes up with a board perhaps will have to either solder in the chip or outsource them through a company that can provide that service. My two cents worth. Regards Cliff Cliff |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3165 |
The 100 pin chip comes in two sizes. The larger size has 0.4mm pin spacing (if I remember correctly) and that is not too hard to solder. Geoff Geoff Graham - http://geoffg.net |
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