Kwinn, yes I've seen the oscillator test circuits in Google, but they only suggested a max frequency of 10MHz. I suppose though, no harm done to try it on 20MHz.
yisiguro, yes the Reset feature of the BS2 has crossed my mind as a possible problem area. I have never connected anything to the BS2-OEM's
Reset Pin, but with the circuit DigitalBob posted, I can see bar MCLR pin 28 is pulled high via resistor RN2 and Vdd on U3, but what mechanism actually calls a reset I'm not sure. But I will try to check that theory out.
Hi yisiguro
Sorry I never answered your question. Yes it does power the "traffic lights sequence" every time and won't download another program.
I had tried downloading any program I had saved to the Editor "Pressing Run" many times while looking, with the scope, at the Xtal, EEprom, and bar MCLR on the chip, then out of the blue up came the debug window and it downloaded "traffic lights sequence", which still runs it's sequence now. So it crossed my mind had I triggered it by touching the bar MCLR pin?
Download has refused to cooperate since.
I read "BASIC Stamp Help" bundled with "BASIC Stamp Editor" software, and I found a section "Connection Troubleshooting".
Its subsection "Run/Identify Test" says:
It Passed the Run/Identify Test but Still Won't Program Reliably
If your USB-connected BASIC Stamp is detected and you see Yes in both columns, but can program only intermittently or get a "No BASIC Stamps Found" or a hardware/communication failure message, try adjusting the Latency Timer Settings.
and subsection "Latency Timer Settings":
In the Advanced Settings window, change the Latency Timer setting to 1 and then click OK.
I checked settings of my USB-UART bridge based on FTDI FT232R, its default latency is 16 msec. It's slow to communicate with BS2.
(edit:)
I also checked settings of another machine which have legacy built-in COM port, but it has no settings about latency. Maybe built-in COM ports with MS's default driver have very little latency.
It Passed the Run/Identify Test but Still Won't Program Reliably
If your USB-connected BASIC Stamp is detected and you see Yes in both columns, but can program only intermittently or get a "No BASIC Stamps Found" or a hardware/communication failure message, try adjusting the Latency Timer Settings.
I was wondering the same thing while having some off-line discussions with Terry...but forgot to bring it up. I recall having similar issues when using a laptop, not so much with using a desktop system though.
I guess this is another question to ask: Terry - what are you using? A laptop or desktop?
DJ
@yisiguro
I have breadboarded a BS2 before and found that it does not work without the Vin line connected to 6-12vdc. Try this, connect a 9v battery or any other power supply in this range(I think) to Vin.
I am not familiar with the BS2 OEM. If it has an onboard 5v regulator, then it should take care of powering Vdd.
I am not familiar with the BS2 OEM. If it has an onboard 5v regulator, then it should take care of powering Vdd.
Same here.
However, the voltage regulator LM2940 has capability of reverse polarity protection, and its quiescent current is only 30mA at non drop out condition. So I do not worry about this situation.
(edit:)
I misunderstood description in datasheet about reverse polarity protection and quiescent current: these are to be applied for VIN, not VOUT.
On the other hand, Basic Stamp Manual says about VDD pin:
if an unregulated voltage is applied to the VIN pin, then this pin will output 5 volts.
If no voltage is applied to the VIN pin, then a regulated voltage between 4.5V and 5.5V should be applied to this pin.
Both BS2 module and BS2 OEM board use similar voltage regulator.
I have two desktop set ups: My old PC running on Windows XP, which has a 9-pin Serial RS232 Port and has installed an older version of Basic Stamp Editor.
My other newer PC runs on Windows 10; this hasn't got a Serial Port, so I purchaced a Parallax USB converter, it also has Basic Stamp Editor installed (the latest version).
Because I know my BS2-OEM did work perfectly well on the old Windows XP PC I have stuck to testing it on that unit. Good point, I wasn't a where the V/Regulator LM2940 has reverse polarity protection. I'll connect up via (Vin) in future.
Many thanks for sorting out my BS2-OEM.
Could you explain how you managed to track down it's problems?
Hi Terry - sure, will do.
I first confirmed your reported issues ("Loopback ok", "no Stamp detected").
After verifying my own BS2-OEM was working correctly, I swapped out your chip set (Stamp and memory) with mine; the problems remained. So, that meant the issue was somewhere else...
With your board and my board unloaded of Stamp and memory, I took resistance measurements (referenced to ground) on all Stamp socket pins and found that there were great differences between my board and yours. In particular, your Stamp MCLR/ pin had a much lower resistance value than mine. That bit of information lead me to suspect the low-voltage detect device (U3). The output of U3 is connected to the Stamp MCLR/ pin. If U3 had failed, it could be keeping the Stamp in constant clear-mode.
U3 was removed and your board came alive. (yay!)
I was able to download a "wiggle all pins" program, and observed your BS2-OEM board functioning as expected (each I/O pin traversing 0V-5V-0V).
This was fun! Thanks for trusting me with the investigation.
Many thanks for sorting out my BS2-OEM.
Could you explain how you managed to track down it's problems?
Hi Terry - sure, will do.
I first confirmed your reported issues ("Loopback ok", "no Stamp detected").
After verifying my own BS2-OEM was working correctly, I swapped out your chip set (Stamp and memory) with mine; the problems remained. So, that meant the issue was somewhere else...
With your board and my board unloaded of Stamp and memory, I took resistance measurements (referenced to ground) on all Stamp socket pins and found that there were great differences between my board and yours. In particular, your Stamp MCLR/ pin had a much lower resistance value than mine. That bit of information lead me to suspect the low-voltage detect device (U3). The output of U3 is connected to the Stamp MCLR/ pin. If U3 had failed, it could be keeping the Stamp in constant clear-mode.
U3 was removed and your board came alive. (yay!)
I was able to download a "wiggle all pins" program, and observed your BS2=OEM board functioning as expected (each I/O pin traversing 0V-5V-0V).
This was fun! Thanks for trusting me with the investigation.
But how'd you manage it being stared at by a bored domestic?
I've put up a separate building that I call Design Central and do all my tinkering in there, so my better half doesn't have to watch me do seemingly incomprehensible things.
Comments
yisiguro, yes the Reset feature of the BS2 has crossed my mind as a possible problem area. I have never connected anything to the BS2-OEM's
Reset Pin, but with the circuit DigitalBob posted, I can see bar MCLR pin 28 is pulled high via resistor RN2 and Vdd on U3, but what mechanism actually calls a reset I'm not sure. But I will try to check that theory out.
Many thanks. Terry
I've sent you a PM.
Dave
Sorry I never answered your question. Yes it does power the "traffic lights sequence" every time and won't download another program.
I had tried downloading any program I had saved to the Editor "Pressing Run" many times while looking, with the scope, at the Xtal, EEprom, and bar MCLR on the chip, then out of the blue up came the debug window and it downloaded "traffic lights sequence", which still runs it's sequence now. So it crossed my mind had I triggered it by touching the bar MCLR pin?
Download has refused to cooperate since.
Terry.
Terry
PM'd you.
Dave
I think the probe of scope does not affect MCLR because input impedance (1M or 10M) of scope is much higher than pull-up resister (10k) for MCLR.
Your right, I think I was grasping at straws.
Terry
Its subsection "Run/Identify Test" says: and subsection "Latency Timer Settings":
I checked settings of my USB-UART bridge based on FTDI FT232R, its default latency is 16 msec. It's slow to communicate with BS2.
(edit:)
I also checked settings of another machine which have legacy built-in COM port, but it has no settings about latency. Maybe built-in COM ports with MS's default driver have very little latency.
I guess this is another question to ask: Terry - what are you using? A laptop or desktop?
DJ
I have breadboarded a BS2 before and found that it does not work without the Vin line connected to 6-12vdc. Try this, connect a 9v battery or any other power supply in this range(I think) to Vin.
I am not familiar with the BS2 OEM. If it has an onboard 5v regulator, then it should take care of powering Vdd.
However, the voltage regulator LM2940 has capability of reverse polarity protection, and its quiescent current is only 30mA at non drop out condition. So I do not worry about this situation.
(edit:)
I misunderstood description in datasheet about reverse polarity protection and quiescent current: these are to be applied for VIN, not VOUT.
On the other hand, Basic Stamp Manual says about VDD pin: Both BS2 module and BS2 OEM board use similar voltage regulator.
I have two desktop set ups: My old PC running on Windows XP, which has a 9-pin Serial RS232 Port and has installed an older version of Basic Stamp Editor.
My other newer PC runs on Windows 10; this hasn't got a Serial Port, so I purchaced a Parallax USB converter, it also has Basic Stamp Editor installed (the latest version).
Because I know my BS2-OEM did work perfectly well on the old Windows XP PC I have stuck to testing it on that unit. Good point, I wasn't a where the V/Regulator LM2940 has reverse polarity protection. I'll connect up via (Vin) in future.
Many thanks Terry
Many thanks for sorting out my BS2-OEM.
Could you explain how you managed to track down it's problems?
Best Regards TerryR
Hi Terry - sure, will do.
I first confirmed your reported issues ("Loopback ok", "no Stamp detected").
After verifying my own BS2-OEM was working correctly, I swapped out your chip set (Stamp and memory) with mine; the problems remained. So, that meant the issue was somewhere else...
With your board and my board unloaded of Stamp and memory, I took resistance measurements (referenced to ground) on all Stamp socket pins and found that there were great differences between my board and yours. In particular, your Stamp MCLR/ pin had a much lower resistance value than mine. That bit of information lead me to suspect the low-voltage detect device (U3). The output of U3 is connected to the Stamp MCLR/ pin. If U3 had failed, it could be keeping the Stamp in constant clear-mode.
U3 was removed and your board came alive. (yay!)
I was able to download a "wiggle all pins" program, and observed your BS2-OEM board functioning as expected (each I/O pin traversing 0V-5V-0V).
This was fun! Thanks for trusting me with the investigation.
Dave
Way to go Dave!
Many thanks for your help in getting my BS2-OEM back working again.
Terry.
Yes, but also the whole business taken as a whole. However, regarding the problem, solving it was also an excellent display of talent.
But how'd you manage it being stared at by a bored domestic?
Yes it was indeed. But how'd you write yours with a really bored domestic watching you write that, and not the same one who watched Dave at work.