allisonlastname wrote:
Strange issue: the RAM doesn't seem to be accepting write cycles. I've checked the connections and they're all correct, so I have no idea what could be going wrong.
The schematic seems to have no issues to me. Maybe double-check NAND wiring (U5A & U5D)? Do you have a logic analyzer? If so - you could check if RAM's /CS & /WE are properly asserted during RAM write cycles.
EDIT: Are you using decoupling capacitors? I don't see any on your schematic nor on the breadboard. To quote BDD:
BigDumbDinosaur wrote:
Each device should be paired with a bypass (aka decoupling) capacitor. Time and time again, we have seen unstable or DOA designs that were victims of nothing more than inadequate or non-existing bypassing. Typical practice places a 0.1µF ceramic (MLCC) capacitor so it is as physically close to the device's VCC pin as possible. Capacitor connections should be as short and direct as possible. I use 50 volt, X7R capacitors in my builds. Bypass capacitors are cheap, don't be shy about using them.
I even like to squeeze them right under the chips - it saves a lot of space and allows the traces to run under the capacitor (especially when doing PCB designs):
Attachment:
cap.jpg [ 68.47 KiB | Viewed 348276 times ]
BigDumbDinosaur wrote:
and3rson wrote:
Just wondering - is there a reason why you're pulling /RST high? DS1813 should work just fine without it.
The pullup inside the DS1813 is weak. An external pullup makes the circuit a lot less noise-sensitive.I actually found its weak pull-up to be a very helpful indicator that I forgot to add capacitors near power-hungry components.
In my case, ESP-01 was often triggering reset during WiFi reconnects, and this issue went away after I added an extra 10uF cap near it.
_________________
/Andrew
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