Can use IMX6 Rex with 4GB RAM?

[tanbakoo]

Hi,
I see in IMX6 Rex layout 4 chipset of DDR3 ram with double t-branch methodology (totally 2GB) and in IMX6 OpenRex it has 4 chipset of DDR3 ram with flyby methodology (totally 4GB) so I have 2 question:
1-Why in IMX6 Rex you use double t-branch while it is recommended for DDR2 ram and not recommended for DDR3?
2-Can I montage IMX6 OpenRex DDR3 chipset in IMX6 Rex to have a IMX6 Rex with 4GB ram?Is it work properly?
Best Regards

[robertferanec]

1) It's up to the engineer to decide. iMX6 supports both topology, read more in iMX6 Design Guide >

2) Yes, you can. You can order 4GB iMX6 Rex modules from VOIPAC webstore: http://www.voipac.com/#iMX6-REX-53342211

[tanbakoo]

Hi Robert,
In Voipac site in PRODUCTS
iMX6 Rex Module - Ultra configuration
( http://www.voipac.com/#iMX6-REX-53342211 ) I see:

Other available configurations (MQO: 10pcs):
• CPU type:
i.MX6 DualLite - 800MHz/1GHz
i.MX6 Dual - 800MHz/852MHz/1GHz
i.MX6 Quad - 800MHz/852MHz/1GHz/1.2GHz
i.MX6 QuadPlus - 1GHz
• DDR3 SDRAM: 512/1024/2048/4096MB
• 4GB microSDHC Class 4 memory card/not supplied
• SPI Flash: 16/32Mb/not soldered
• 10/100/1000 Mbps Ethernet/not soldered
• High speed 60-pin ground plane socket: 1pc/2pcs
• Available temperature range:
0°C to +70°C commercial temperature range
-20°C to +70°C extended temperature range
-40°C to +85°C industrial temperature range

Other available SW:
• Android kitkat 4.4.2

all of these configuration have a same PCB Bare Board file and only BOM will be change?

Best Regards

[robertferanec]

Yes, all iMX6 Rex modules have same PCB, but different BOMs.

[ranaya]

This is may be the exact post I am looking for, and to add my question.

The IMX6 Rex seems to be using DDR3 RAMs in T-branch topology as tanbakoo noted, so according to your previous comment we should be able to use 4GB RAM with that topology right ?

If it's the case how can we use MT41J256M16HA-125:E chip to achieve 4GB without modifying the IMX6 Rex Layout ? Since the width of the chip is 16, is
4Gb / (32M × 16 × 8) × 4 SDRAMs × 2 ranks the correct configuration for 4GB ?

Thanks in advance

[robertferanec]

You can not use MT41J256M16, you need a different chip. This may help you: http://www.fedevel.com/designhelp/fo...or-ddr3-memory

[ranaya]

robertferanec Thanks for your reply Robert, could you please kindly elaborate why I cannot use that one ? If it's not usable, what could be an appropriate chip we can use to achieve 4GB RAM with IMX6 REX layout without doing nay modification ?

[robertferanec]

Because 256 is smaller memory chip comparing to 512. Be aware, there is only 1 rank, not 2.

[ranaya]

Okay, now I am bit confused.
1.) If we consider the existing RAM chip (MT41J128M16HA-15E TR) on Rex, that's being 2Gbit per chip, we will get total 1G Byte of RAM if rank = 1 is used, won't we ?
[128M x 16(device width)] × 4 (no of chips) × 1 (rank) = 8192 Gbit = 1 GByte (But Rex said to have 2 GByte ?)

2.) In same way 4x MT41K512M16HA chips, the total RAM would be equivalent to 4GB right ? If I am not mistaken, 4 of these RAM chips give us :
[512 x 16(device width)] × 4 (no of chips) × 1 (rank) = 32768 Gbit = 4 GByte
Correct me if I'm wrong !

3.) So I can replace MT41J128M16HA with MT41K512M16HA without any modification ?

I'd be grateful if you could answer these question, one-by-one.

Thanks in Advance

[robertferanec]

I do not know exactly what memories VOIPAC uses on the modules (they are different between variants). The chips they use may be different from the chips used in the schematic - depends on module memory size.

MT41X128X16 => 2Gb x4 => 8Gb / 8b = 1GB in total
MT41X256X16 => 4Gb x4 => 16Gb / 8b = 2GB in total
MT41X512X16 => 8Gb x4 => 32Gb / 8b = 4GB in total

[ranaya]

Hi Robert,

In short can I use this RAM chip to replace the IMX6 Rex module RAM ? I don't need to increase the RAM size, this has the same features as original REX chip 'MT41J128M16HA-15ETR' except the clock rate (this one 800MHz) !

http://www.digikey.com/product-detail/en/micron-technology-inc/MT41J128M16JT-125-K-TR/557-1611-1-ND/4172109

Thanks

[robertferanec]

The easiest way to select memory chip is to use the same type of memory as used on iMX6 Rex, but different memory size. Frequency must be at least 533MHz (DDR3 1066). Any memory you would like to use, you may need to test it by yourself.

Always when we buy a different kind of memories, we run DDR3 calibration ( http://www.imx6rex.com/software/how-...ation-on-imx6/ ), then we stress tests the memories and run them also in environmental chamber. Here is an example of tests we are running: http://www.imx6rex.com/open-rex/soft...ental-chamber/

I know I did not answer your question directly, but you should be able to answer it by yourself based on my answer

[ranaya]

Dear Robert, thanks for clarifying this. Well I actually though even the VOIPAC promotes the same REX you've been developing. So now the problem of the chip mismatch is sorted !

This question is more related to the die arrangement of the chip, what I exactly wanted to know was 'how we can use twin die RAM chips with REX' (since most of the higher densities are in twin die arrangement). But I figured out few extra signals are required to achieve the operation. So in nutshell, for high density RAMs the rex layout need to be modified a bit. Another issue is the lack of the availability of well known RAMs (Micron, Shynx) in the market. I plan to switch to AS4C256M16D3A-12BCN to achieve total of 2GB in T topology with REX.

Thanks

[robertferanec]

Yes, you are correct. Two die memory chips can not be used with REX, unless you modify the layout.