Jumpers have no effect (doesn't change between 4116 and 4165/256)

[giobbino]

This is quite a trivial issue, but since it took a little to understand what was wrong, I just want to leave a clue (also because some note inside the code are in italian... perfect for me, but not so good for somebody LOL).

Issue: no effect moving the three jumpers on High or Low.

Looking at the source code, in the function.ino -> selchip() there's a static declaration about the three values: off, 4116 and 4164 from the A6 pin: below 10 is OFF, between 10 and 200 is 4164, otherwise is 4116.

In my configuration, the setting for 4164 returns about 720-730 and for 4116 is above 1800.

So if you experienced the same problem, you should open the source code, find the selchip() function and activate the line:

Serial.println(MREAD);

Then compile, upload and run the code on your RAM tester, and open the serial monitor with Ctrl+Shift+M ( ** CHECK THE SPEED IS 9600!)

Check the three jumpers setup: no jumper, 4164 and 4116.

Then come back in the selchip() function and fix the lines with the correct values:

if (MREAD<10) {//4164 <<< put a value a little above the "no jumper" config. if it is zero, this line is already ok return 0; } else if (MREAD<200) {//4164-256-32 <<put a value a little above the "2164 jumper" config. in my case was ~730 so I put 800

This should fix the issue.

---

I have to say I used a "nano-clone", drop-in replacement board, the Mini-EVB LGT8F328P-LQFP32 @ 16MHz. This board should be an almost perfect clone of an Arduino Nano, but I can't 100% guarantee about that.

Cheers, Giovi

[zeus074]

this may depend on the supply voltage and resistance values, I calibrated them according to the settings I had. to avoid problems, the intervention range can be increased. check with mine and in case I increase the value. I got these values: (when I write the code) 0=key on 4164 510=empty key 1024=key on 4116

1800 seems like a very high value to me.

[giobbino]

I think you mean 0=empty and 510=key on 4164 (your comments in the code seems to be different from the source code)

I got: 0=empty; about 720=4164; about 1815=4116.

I could depend by the different board (Mini-EVB LGT8F328P-LQFP32) I used, but I'm not really sure about it, since I used that board in many projects (it was 1/2 the price of an Arduino Nano clone so I bought some of them) and I never experienced any issue. However, no problem at all, just a matter of setting the value in the source code.

To make the things simpler, I slightly modify your code:

I added two lines at the top of the main sketch...

define RAM_NDEF 10 // < 10 = empty

define RAM_4164 1000 // < 1000 = 4164

...and I modify the selchip() function accordingly if (MREAD<RAM_NDEF) { //no jumpers return 0; } else if (MREAD<RAM_4164) { //jumpers on 4164 return 1; } else { //jumpers on 4116 return 2;

[zeus074]

Yes you are right, there must be an error in the comment, because without jumper it must be 0. As soon as I can do some tests and find the pcb, I update the comments and the code

0v = no jumper low value = 5v (4164) high value =12v (4116)

This is the resistive divider, if you have a too high value it could be that the resistances are of different value, the voltage higher, or a different reading of the Arduino DAC. If you want you can lower R15 to 1K6 to bring the reading back into the parameters.

[giobbino]

Thank you. Soon or later i will build another RAM tester with an Arduino Nano, just to see if the problem is the Arduino Nano vs clone or the resistors. However, generally speaking, I see no needs to change the hardware when you can solve changing the software LOL... With the new values it's working, and it's enough for me.

I also slightly modify you software, adding a FAST / SLOW mode on all modes. The SLOW mode makes more test per bit, writing 0 and 1 alternately. However I didn't see any difference on the RAM chips that were supposed to be bad , so I don't know if there's any good doing that.

Next step, is to test those "bad" (bad?) RAM ICs again in a C=64 and see if they are really bad or not.

[giobbino]

I've built a second RAM tester, this time using a chinese Arduino Nano. All the others components remain the same, from the same seller and lot.

The values changed dramatically: now I have a value around 185 for the 64/256 setting, and around 473 for the 4116 setup.

Weird, isn't it?