FeRAM FM18W08 for LoROM and HiROM get black screen

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Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

FeRAM FM18W08 for LoROM and HiROM get black screen

Post by Kayumba »

Hi everyone,

I trie to use schematic of soniccd123 for FeRAM FM18W08 for my custom SNES Board ( thx soniccd123 for sharing ).
But I get black screen.
I tested my super cic chip and EPROM with other board and it works great.
Do you have any idea, where can be error ?
Can somebody help me to find mistake, please.

Image

Image

FM18W08
pin 20 (CE#) = 4081 pin 10 for HiROM, pin 3 for LoROM
pin 22 (OE#) = /RD (SNES EDGE pin 23) + (4071 pin 13 for HiROM, pin 1 for LoROM)
pin 27 (WE#) = /WE (SNES EDGE pin 54) + (4071 pin 8 for HiROM, pin 6 for LoROM)

27C322
pin 11 (CE) = /ROMCE
pin 13 (OE) = GND

2 X Multiplexers 74*257
pin 2 (OE#) = /ROMCE
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aquasnake
Posts: 515
Joined: Fri Sep 13, 2019 11:22 pm

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by aquasnake »

Maybe the access speed of FRAM is too fast. Generally, it is recommended to use ram of more than 100ns, and some SRAM/FRAM of -7 ~ -10 may have problems
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by Kayumba »

aquasnake wrote: Tue Mar 01, 2022 3:09 am Maybe the access speed of FRAM is too fast. Generally, it is recommended to use ram of more than 100ns, and some SRAM/FRAM of -7 ~ -10 may have problems
Hi,
Thank you for answer.
How can I know the speed access ?
All what I see on FRAM is : FM18W08-SG (and one very long serial number: A 19319004053)
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aquasnake
Posts: 515
Joined: Fri Sep 13, 2019 11:22 pm

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by aquasnake »

Kayumba wrote: Tue Mar 08, 2022 4:43 pm
aquasnake wrote: Tue Mar 01, 2022 3:09 am Maybe the access speed of FRAM is too fast. Generally, it is recommended to use ram of more than 100ns, and some SRAM/FRAM of -7 ~ -10 may have problems
Hi,
Thank you for answer.
How can I know the speed access ?
All what I see on FRAM is : FM18W08-SG (and one very long serial number: A 19319004053)
The chip will be marked with the model number, and the suffix at the end usually indicates the SRAM / FRAM speed.

For example, - 5, - 7, - 10, - 12 indicates that the access speed (read-write cycle) is 55ns, 70ns, 100ns and 120ns

Empirically,NES and SNES cannot use SRAM / FRAM which is too fast
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by Kayumba »

So here Feram with serial number: A 19319004053
Last « 3 » means that speed is 30ns ?
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aquasnake
Posts: 515
Joined: Fri Sep 13, 2019 11:22 pm

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by aquasnake »

FM18W08: 70 ns Access Time
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by Kayumba »

aquasnake wrote: Fri Mar 11, 2022 12:30 am FM18W08: 70 ns Access Time
And what do you think ?
70 ns it’s too fast ?
What can I do ?
soniccd123
Posts: 46
Joined: Sat Jun 27, 2020 12:01 pm

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by soniccd123 »

Hello, its been a long time since I last logged in, sorry for being so late, but college got me hard for the last 12 months

Which game are you trying to load? Have you checked your solder joints? Are the jumpers are set correctly? Its been a long time since I last used this PCBs, I have been using my new flash based design (which I think I may have not posted here?), but they were working correctly with all games I tried, even 32Mbit ones
arquino
Posts: 2
Joined: Thu Aug 18, 2022 6:44 am

Re: FeRAM FM18W08 for LoROM and HiROM get black screen

Post by arquino »

soniccd123 wrote: Tue Aug 16, 2022 12:38 am Hello, its been a long time since I last logged in, sorry for being so late, but college got me hard for the last 12 months

Which game are you trying to load? Have you checked your solder joints? Are the jumpers are set correctly? Its been a long time since I last used this PCBs, I have been using my new flash based design (which I think I may have not posted here?), but they were working correctly with all games I tried, even 32Mbit ones
Good morning mate! I'm from Brazil, so I'm sorry if the English isn't very correct.
I found your project on the web and I was very interested because it uses save without battery.
I had some pcb's made but I couldn't get it to work. I believe you are making the same mistake mentioned above.
I didn't find any reference on how to byteswap in rom snes for 27c322, can you explain to me how this process is?
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