Do you have the crystal's datasheet, and the way it's connected to your circuit or MCU ?My 32Khz crystal does not work on my breadboard. What are the reasons for this? What about 4Mhz or 10Mhz?
- Is it because of static? Should I get a FR4 as an anti-static?
- Should the crystal be as close as possible to MCU?
Thanks for the reply. Makes sense.maybe you wrecked it. they easily break inside.
try degrease it with lighter fluid but be careful- the backside from breadboards is often glued and that will dissolve from lighter fluid.
There are at least 20 possible reasons.
For instance the legs (pins) are very thin they dont match for breadboard. you need a small carrier, like in the photo.
Indeed you shouldnt bend 32 KHz crystal pins abnormally or sharply or even at all. In old times, the small cylinder was hold in place with a wire bridge.
I noticed when I try to see pulses from the LED connected to the microchip, the pulses I barely see. the LED just blinks a few seconds (oscillates) and then its fully on for a long time. Would this be the cause of the crystal and breadboard together not making the pulses work properly?Yes, crystals can be finicky on breadboards.
When doing a PCB layout you really need to watch how you place your components. Keep the traces as short and straight as possible to the IC pins. Watch out for unintentional inductance and capacitance. Follow the recommendations for the feedback resistor, loading capacitors and series resistor.
If the 32768Hz crystal is to be used for accurate time-keeping you need to use a trim capacitor so that you can trim the oscillation for better precision.
I ordered the crystal cylinder 32.678Khz with two thin pins. The info didn't come with a datasheet but Im sure you know the cylinder crystal. Pretty small.Do you have the crystal's datasheet, and the way it's connected to your circuit or MCU ?
Are you using the crystal to oscillate an MCU, and if so, how exactly did you connect it?I ordered the crystal cylinder 32.678Khz with two thin pins. The info didn't come with a datasheet but Im sure you know the cylinder crystal. Pretty small.
Do you know a component I can add to the breadboard that can hold those thin pins? I remember I saw a youtube video where someone had two screw like components with holes within them that can hold the crystal pins inside, I don't know what the name of that component is.
This is how it is connected, showed in the picture.Are you using the crystal to oscillate an MCU, and if so, how exactly did you connect it?
You need to clarify where are you connecting the LED?I noticed when I try to see pulses from the LED connected to the microchip, the pulses I barely see. the LED just blinks a few seconds (oscillates) and then its fully on for a long time. Would this be the cause of the crystal and breadboard together not making the pulses work properly?
Yes, with sensitive pins there is such a PCB layout technique using what is known as a guard ring.Also, since you brought up unintentional inductance and capacitance, is it possible to add a ground shield to the crystal? Would this help insulate the crystal from surrounding components?
I consider myself an expert in the 8051 architecture. A few years ago I had the same issue as you, until I took into account four simple facts that helped me solve the problem:This is how it is connected, showed in the picture. Capacitors are 15pF.
Same here. I don't use solderless breadboards, I keep the leads short and as close to the chip as I can get them.I have used a 32 Khz crystal on a breadboard with no problems.
If its a tiny watch crystal - those tiny little leads won't touch the sides in a breadboard.Just guessing...plug-in breadboards have some capacitance at each connection. I really don't know if it's enough to stop a crystal oscillator.
Sorry for not replying to anyone yesterday. I was a little busy.I consider myself an expert in the 8051 architecture. A few years ago I had the same issue as you, until I took into account four simple facts that helped me solve the problem:
This last issue gave me quite quite a headache a few years back, until I discovered that the default setting of my programmer was the use of an external oscillator... that's why my crystal and caps weren't working at first.
- Crystals have a series equivalent resistance
- Crystals have an internal capacitance
- Most MCU's have a maximum allowed capacitive load at their oscillator inputs (which must include the crystal's inherent capacitance), if you exceed it then their internal oscillator won't work. If the value is too low, then the oscillator might not start. Check the MCU's datasheet.
- Some MCU's require that you select (through an internal setup bit, which is set or cleared at the moment of programming) if they're going to run using their own internal oscillator (which is connected to the external crystal and caps) or if you're going to run them through an external oscillator. That is, if you're going to use just the crystal and caps, or if you're going to clock them with a perfect TTL square wave being generated by an external oscillator. This option is normally found in the device programmer that you're using.
I suggest you double check on the points I just mentioned before you go any further
EDIT: In my case, I like to use Atmel's 89LP4052 MCU, which won't accept a total capacitive load at its oscillator inputs of more than 20pf ... in your case, you're using 30pf plus your crystal's capacitive load ... but you haven't mentioned which specific MCU you're using
Have you seen a component that can be soldered onto the PCB board track that is like a crystal carrier? I remember seeing someone on youtube that used two screw-like components with holes in them to hold the crystal pins tightly.If its a tiny watch crystal - those tiny little leads won't touch the sides in a breadboard.
Maybe make up a patchboard of just 2 holes of Veroboard with a couple of lengths of 18 or 20SWG tinned copper wire, the crystal can be tacked onto the solder joints on the patchboard.
In the the following file:Im using ATEMGA8-16PU microcontroller.
Would a higher value of pF be preferable for a 32.678Khz crystal in any case as default load capacitance? I was told a maximum of 22pF is enough. Some others say its between 2 - 22pF, but as you said in point 3 I think it depends.
by Jake Hertz
by Jake Hertz