Display with integrated controller

[lpcware]

Content originally posted in LPCWare by schisanoa on Thu Jan 16 02:16:40 MST 2014
I need to interface to LPC4078 a display with an integrated controller with 16bit data bus, I also have a SDRAM on the EMC, can I connect also the display on the EMC or there may be something wrong in doing this?

thanks in advance

[lpcware]

Content originally posted in LPCWare by schisanoa on Fri Jan 17 09:21:29 MST 2014
Ah ok, also with YAFFS or UBIFS I must do the ECC by hand.

Is there a non-commercial solution that allow me to use the NandFlash(also if require a porting)? Or is faster use YAFFS and do the ECC by hand?

The NandFlash was selected from my boss because he doesn't want a socket connector(like the SD card connector) and it is soldered directly on the pcb.
I need to write and read data a lot of time, so I'm not sure of the life of the NOR flash, and I need at least 1GB(8Gb) and I don't find a serial NOR or a SPIFI capable enough.

The display also was selected from my boss, and he want a display with controller integrated(so I changed from LPC4088 to LPC4078, without lcd controller, little bit cheaper).

My actual supposed memory layout will be:
-Internal flash: bootloader and some code.
-Internal RAM: varaible and stack
-SDRAM: data
-SPIFI: expansion flash for CODE
-NandFlash(not sure) : data file storage
-LCD, with controller HImax, and 16 bit data on EMC (with a buffer on DATA bus as you suggested)

what do you think about?

thank
Alessio

PS: An SPI Nand Flash may be another solution or no?

[lpcware]

Content originally posted in LPCWare by wmues on Fri Jan 17 06:06:38 MST 2014
Yes, you will need a special file system as YAFFS, JFFS2 oder UBI/UBIFS for NAND.
Additional, you will have to do ECC "by hand".

NAND flash file systems are available for Linux today. Using a non-Linux-System you have 2 options:
a) port a flash file system from Linux to your target.
b) buy a comercial embedded flash file system.

If you use a (serial) NOR flash, you will not need ECC, and maybe you will find a free embedded file system doing wear leveling for NOR flash.

If you use emmc or SD-card, the memory chip will do all ECC and wear leveling for you, and you only need a (normal) block file system (FAT etc).

IMHO, if your CPU has a SD card interface, it's very easy to add a (micro)SD to your system and have all data and program files on this card. It's very convenient to put the card into a PC card reader and have access to all your data & code from the PC.

My favourite memory layout is:
- internal flash: bootloader, reading code from SD card and placing code in SDRAM.
- internal ram: some variables, some fast code and STACK.
- SDRAM: code, data, etc
- SD card: code, additional files

PS: as you are using NXP LPC4078, I do not understand why you are using a display with integrated controller (maybe NON-TFT?). TFTs without controller are cheaper, and you can spend the money for a SD card...

Even TFTs with resistive touch are cheap, and you will have a good user interface. Resistive touch is cheaper as some buttons.

regards
Wolfgang

[lpcware]

Content originally posted in LPCWare by schisanoa on Thu Jan 16 16:39:19 MST 2014
Sorry, I will take take a few more minutes of your time.

At first thanks for your reply, I spent lot of time this evening after read it on web reserch about the Nand flash.

If I understand I can't use the Nand flash with a simple fatfs or something similar, right?

I need a Nand file system driver, that allow me to manage wear leveling, ECC, file, property and folder, ecc, right?

Do you know if UFFS or YAFFS may be ok to do this?

If I use a Spifi or a emmc Do I need to manage wear leveling ecc..?

Thanks
Best regards
Alessio

[lpcware]

Content originally posted in LPCWare by wmues on Thu Jan 16 11:53:50 MST 2014
Alessio,

adding a NAND flash to the SDRAM data lines will have only a little impact on the signal integrity, because the wires to the NAND flash will be short.

If I have a choice, I would always use other data & address lines for a 2nd memory. You will have less problems with EMI compliance.

Using a bare NAND flash will force you to add a nand flash file system driver, doing all the ECC, wear leveling etc. in software.
Do you really want this?

You might be better off using
a) serial NOR flash (SPIFI or SPI)
b) emmc (using SD card interface)
c) microSD card

regards
Wolfgang

[lpcware]

Content originally posted in LPCWare by schisanoa on Thu Jan 16 09:03:12 MST 2014
Thanks for your quick reply.

do you think that I may have the same problem also if I add a NAND flash on the databus?(8bit databus)

do you suggest use of a buffer also for the NAND?


regards

Alessio

[lpcware]

Content originally posted in LPCWare by wmues on Thu Jan 16 02:48:12 MST 2014
You may experience a distortion of your SDRAM signals, and you may experience EMI problems.

I would not do this.

Instead, you may want to insert a 16bit buffer on D0...D15, which is only enabled if the /CS of the display is on.

OR: use D0...D15 for SDRAM, and use D16...D31 for display.

Do not share signals between SDRAM and display.

regards

Wolfgang