Post AxdrT50NrimpuhU3EG by fmn@mastodon.social
 (DIR) More posts by fmn@mastodon.social
 (DIR) Post #AxdpLMlTkglmljhqGu by mntmn@mastodon.social
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       have you ever seen that if you access a certain address in a ddr3 chip, it kind of crashes and needs to be reset to work normally again?
       
 (DIR) Post #AxdrBB26iQcfObkkoC by mntmn@mastodon.social
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       it doesn't like addresses that end in 0xff7f01c
       
 (DIR) Post #AxdrT50NrimpuhU3EG by fmn@mastodon.social
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       @mntmn can't that be memory controller register or something along those lines?
       
 (DIR) Post #AxdrXXnAmJo8LwQuau by mntmn@mastodon.social
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       @fmn not under normal circumstances
       
 (DIR) Post #AxdzRRy2JyCGBR7TUm by mntmn@mastodon.social
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       omg finally solved this problem... it was unstable/sagging VTT / VTTref because 2022 me didn't consider that all that address termination actually needs to sink some current
       
 (DIR) Post #AxdzaCs7oZ6pyLWvAW by mntmn@mastodon.social
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       i guess it started to fall apart electrically when the memory addresses (seen as binary) would contain a big lump of 1s
       
 (DIR) Post #AxdzfNO692p62AwyQq by mntmn@mastodon.social
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       this might not look like much but it's a big pain relief for me
       
 (DIR) Post #AxehfIXYZ04Mz19BwW by yannsionneau@mastodon.online
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       @mntmn What was missing/is the solution then?I'm a noob in DDR.Missing decoupling caps on Vtt?
       
 (DIR) Post #AxewSyQ132e4PlCYKm by mntmn@mastodon.social
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       @yannsionneau yeah i think traces from vtt regulator to vttref regulator not sufficiently thick, and not enough capacitance near termination array
       
 (DIR) Post #Ay0btaF1Duelgl1Vo0 by ozel@chaos.social
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       @mntmn I feel ya! just got a week of staring at litex bios sources and the sdram_bist command behind me