Rev6 questions - LDR, contents,?

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1 year 5 months ago #9407 by MikeS
Trying to figure out how an LDR can work on a Classic Rev6. The schematics don't show any pullup, and the code doesn't set the internal pullup.

Also, what's the p/n for the suggested LDR? Just a common (but getting less so) CdS photocell?

Also, it's not clear what actually comes in a Rev6 kit - the construction manual lists parts and instructions for a front panel, are the parts included for use on a user-supplied PCB, or ???

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1 year 5 months ago #9410 by Ty_Eeberfest
The kit includes the LDR. There's no place for it on the PCB, the premise being that the main PCB will end up inside a case and the LDR needs to see outside the case. People usually do something like attach it to a piece of perf board (often along with the setting button) and fit it to some appropriate spot on their case.

In case you want to buy an LDR elsewhere, this is from an old post of Ian's:
"It is a GL5516, nominal 5k"

There actually is a pull-up resistor for the LDR. It is hiding on the power supply section of the schematic. It's a 10K resistor, callout is R11. The schematic shows it feeding a line called "DLS" which leaves the board on connector "CONN_FRONT" then reappears on the next page as "LDR". If you compare connector pin numbers you can see that DLS and LDR are the same signal. Prior to Rev.6 that signal was called "DLS" on the external components schematic, something appears to have gotten lost in the revision process.

Look into it later when the dust is clearing off the crater.

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1 year 5 months ago #9411 by MikeS
Thanks. Kind of an odd place to put the pullup on the schematic (I was looking on the "front panel", near the connector, and near the AVR input), but I see it after you pointed it out.

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1 year 5 months ago #9412 by Ty_Eeberfest
I agree but it's not up to me to decide how the schematics and docs are done. It needs to be on the Clock PCB schematic page, not on the Front Panel page, because the PCB layout derives directly from that schematic, but the location in that schematic could be better! The DLS vs. LDR markings on the other hand are an outright error that I will mention to Ian.

Look into it later when the dust is clearing off the crater.

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1 year 5 months ago - 1 year 5 months ago #9413 by MikeS
One more question. The construction manual says: "Install one or other of these options (either RTC or WiFi). Do not install both! The usual time source for this board is an on-board ESP8266 WiFi module, unless you specifically want to use the battery backed RTC (Real Time Clock) module. You can’t use both together! If the clock detects an RTC is installed, it will disable the WiFi interface."

But, the user manual (v352) says: "The clocks can use either a battery backed RTC module or a WiFi module.
If you install both, the WiFi module will set the RTC module to keep it up to date. After 5 minutes when no information is received from the WiFi module, the clock will revert to using the RTC module."

Which is correct?
Last edit: 1 year 5 months ago by MikeS.

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1 year 5 months ago #9414 by Ty_Eeberfest
The second one is correct. This is what the code says, starting at Line 962:
  if (useWiFi > 0) {
    if (useWiFi == MAX_WIFI_TIME) {
      // We recently got an update, send to the RTC (if installed)
      setRTC();      
    }
    useWiFi--;
  } else {
    // get the time from the external RTC provider - (if installed)
    getRTCTime();
  }

useWiFi is set to MAX_WIFI_TIME (which is 5 minutes) every time a time update is received form the WiFi module.

Personally I don't see any need to install an RTC module unless maybe you plan on making your clock portable, in which case it could use WiFi at home and maintain time using the RTC when away from home. Or something.

Look into it later when the dust is clearing off the crater.

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