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5 Renesas RX23E-B controllers

Jan Cumps

What the title says . Good analogue front end, low noise, many bits ADC. None of that ARM rubish :)

image

  • in reply to Jan Cumps

    Interesting point,  . As I’m relatively new here, an update on this thread made me revisit the whole discussion.

    In a previous PCB design/manufacturing role (about 5 years ago) we still received some MCUs in trays, mainly for lower volumes. They were quite convenient for prototyping.

    Maybe it’s more common now to default to reels depending on order size.

      , glad to see this moving again!

  • in reply to Jan Cumps

    So this has been on the backburner for a year - time to pick it up again.

    how I left it:

    • schematics mature for most parts
    • all components at home, in a single box
    • parts of the PCB done, for some modules.

    I'm going to restart the PCB from scratch.

  • This is the scope that I've set for the PCB I'm designing. Based on Renesas' starter kit:

    image

    green: part of my board

    blue: I offload to separate plug-in PCBs

    red: I don't use, and make the relevant microcontroller pins available "non-committed".

  • I'm making progress. The schematic is ready for anything that is not related to the analogue front end. I had to get that out of the way, before focusing on that part;

    link to all posts

  • in reply to jc2048

    I will keep this in mind. I bought "a lot" of 1206 capacitors. I chose that size because they are easy to switch out.

    image

    I ordered enough to cover the "not bulk capacitance" spectrum. And then some ...

    1p - 8.2p
    10p -82p
    100p - 820p
    1n - 8.2n
    10n - 82n
    100n - 22µ

    If I manage to get the board designed (daytime job creeps into the nighttime at the moment), I can learn some more about properly designing the clock  circuit ...

  • in reply to Jan Cumps

    How curious. It would still work (it would probably work without any load caps and just the pin capacitance), but it would be a bit skittish and the RTC isn't going to keep very good time.

  • in reply to jc2048

    I used one of the Renesas reference designs: 

    image

    BOM

    image

    (schematic and BOM source Renesas website)

    The hardware manual (§9.3 and §9.5) contains the calculations, but I didn't use them.

  • in reply to Jan Cumps

    Where did the load caps come from? They look low in value to me.

    If the 32.768kHz xtal is cut for 3.7pF, then assuming a pin/track value of something like 1.5pF (if you keep it compact and close to the pins), 5.6pF might work better. (5.6pF+1.5pF)/2 = 3.55pF

  • The clock part. I'm going very slow - daytime job is hectic at the moment

    image

  • The power part broken out

    image

    and the timer breakout for AC excitation / bias generation

    image