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Yesterday I received by 23LC1024 SRAM with 1 Mbit memory.

I tried to search for some libraries and ways how to connect it.

So I searched around on internet first for the connections and saw some different ways of doing it, especially regarding the pullup resistors.

E.g. in Example1 two resistors are mentioned for pin 3 and 7. In Example 2 only one resistor is used. In YouTube example 3 three resistors and a capacitor is used. See around 5:25.

My questions:

  1. Is one of those three better (and why)?
  2. Is the capacitor in the youtube example 3 connected to GND or 5v? I cannot map the schema with the breadboard since the capacitor should run between +5 and GND but I don't see the +5 or GND connection (depending on where the capacitor is connected to which I cannot see or deduce).

Btw, I got it working with the 2 resistor solution but just wondering if example 1 is good enough or example 3 is better.

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It's better to use external pull-up resistor at least on CS. It's because MCU pins are configured as INPUTs without pull-ups just after the startup/restart before it gets into the setup().

Also I'd recommend decoupling capacitor as close as possible to the SRAM power supply pins (between Vcc and Gnd). You can google what the decoupling capacitors are (they are also called bypass capacitors).

Edit: First two examples are supposed to be on bread board. So it's not so hard just rewire it, if you have to use for example /HOLD too. However the third example is soldered on prototype board and therfore it's not so easy to rewire it. That's why NU and /HOLD inputs are connected to the Vcc through 10k resistor. If you have to use /HOLD in the future, it's easier to just solder new connection, than rewire hardwired connection to the Vcc.

About decoupling caps - there are even sockets with builtin cap: 8pin socket with decoupling capacitor

  • thank you very much ... some more reading to do, thanks for the right naming/functionality of the capacitors. In the example of the youtube video (3th example) at 5:25, pins 1 and 3 (and 7) have a resistor and the capacitor is going from those resistors to either GND or +5v (I cannot see) but in the schematics the pins 1, 3, 7 and 8 all goes to the capacitor from +5 to GND so I do not see how the schematics and the breadboard map? Can you explain this? – Michel Keijzers Apr 6 '17 at 9:27
  • @MichelKeijzers Updated. Btw, it's even more difficult if you have custom board :D – KIIV Apr 6 '17 at 10:01
  • Thank you again KIIV .. for the coming months I will stay away from prototype boards probably ... so I will use the breadboard solution I have now, but add the capacitor on the breadboard as in example 3. Still not sure exactly how to place the capacitor in my case, however, I will first read and maybe it gets clear automatically. – Michel Keijzers Apr 6 '17 at 10:09
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    @MichelKeijzers Like this: i.imgur.com/vRvhIhy.png (it's pretty much the same for 8pins chips) – KIIV Apr 6 '17 at 10:13
  • Thanks ... so in my case in bing.com/images/… I have to put e.g. a 0.1nF between pins 4 and 8? – Michel Keijzers Apr 6 '17 at 10:28

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