Propeller fried ???
Propeller fried ???
I have made a veroboard with a 40-Pin Dip Propeller, very similar to the protoboard.
This board worked at the spot with downloading to RAM. With downloading to EEPROM i had a success rate of 100%, but with executing from EEPROM succes rate was only 80 to 90%.
Reason probably is, that i use ATMEL 24C256 devices, , which are specified for 5 Volt operation.
So i today connected them to 5V and added a 1.47K resistor to pin 29 (SDA), but none in between Pin (28) and SCL.
After applying power, my 3.3V power rail ran up to 4.2 Volts and no more access to the EEPROM was possible.
I tried this several times and sometimes the 3.3Volts stabilizied to 3.3Volts and i got my EEProm-progams running.
But now all communcation to EEPROM is dead, cannot write to or read from EEPROM anymore.
Is PIN 28 a read/write Pin, then i know what i did ( need a new prop ?)
I have made a veroboard with a 40-Pin Dip Propeller, very similar to the protoboard.
This board worked at the spot with downloading to RAM. With downloading to EEPROM i had a success rate of 100%, but with executing from EEPROM succes rate was only 80 to 90%.
Reason probably is, that i use ATMEL 24C256 devices, , which are specified for 5 Volt operation.
So i today connected them to 5V and added a 1.47K resistor to pin 29 (SDA), but none in between Pin (28) and SCL.
After applying power, my 3.3V power rail ran up to 4.2 Volts and no more access to the EEPROM was possible.
I tried this several times and sometimes the 3.3Volts stabilizied to 3.3Volts and i got my EEProm-progams running.
But now all communcation to EEPROM is dead, cannot write to or read from EEPROM anymore.
Is PIN 28 a read/write Pin, then i know what i did ( need a new prop ?)
Comments
So i think i fried pin 28 (SCL line).
*Peter*
P.S. As the SCL line works fine it is very possible that the pullup only needs to go to 3.3V as well.
Post Edited (Peter Jakacki) : 4/12/2008 7:42:52 AM GMT
so i hooked 2 LEDs to pins 28 and 29 and started a small program to let them flash. They did. However scoping the pins showed,that pin 28 has a voltage swing of 0 to 3,3V, while pin 29 only shows 0,5 to 3,3V. this is a 8 LED bar,so i scoped the other pins to. all have a voltage swing from 0 to 3,3V, only pin 29 has 0,5 to 3,3V.
i have run FemtoBasic to check the pins for input, but i dont know the syntax for INA
10 A=INA 28
20 B=INA 29
30 PRINT A,B
40 GOTO 10
didn´t work.
You know that with the power off you can check to see if a chip has fried it's pin by using your trusty old meter on diode check. Red probe on ground and with the other probe you are measuring the internal substrate diode which should all be in the same ballpark. Same goes if you put the black probe on the supply pin and check that way as well.
*Peter*
pins 28 and 29 work as inputs and outputs. i have now replaced all 3 EEPROMs and reprogrammed new ones. the EEPROMs are selectable via a rotary switch. all 3 were fried;i dont know why.
but those are only 2$ parts and the propeller has survived .
I have now booted from different EEPROMs appr. 30 times without a failure.
thanks to all for your help.
But the 5V variants worked with 3.3V during programming always and during booting 80-90%. Now that i feed them with 5 Volts it looks much better (with 1.47K series resistor and 10K pullups).
PS.: just experienced first fail to boot after appr. 100 boots. that's ways better , than before; but not reliable enough. I also encountered,that misboots occur more often, when battery operated,than when fed from a power supply ???
i plan to give a demo of the power of the propeller to some companies next week. currently they use high perfomance pc equipment and expensive hardware, like X/Y/Z controllers, etc.
One of my plans is to show, that the prop can run off a single 9 Volt NIMH battery for at least 6 hours.
Yesterday charged (9,54 Volts), today it has still 9 Volts( 8,65 Volts under load) after 300 reboots for my EEPROM testing.
For the demo i will store different programs in the EEPROMs.
For my private use i store functional programs into one EEPROM, testing/debugging is done either in RAM or on another EEPROM.
Currently i have 3 EEPROM sockets,which i can select via a rotary switch
There is no more hardware on the board. All plug-in modules have no caps at all and function properly.
That might be causing slow rise/fall times on the 3V3 either interfering with Propeller reset or Eeprom operation. You could try removing it and see what that does.
You could try adding caps, and does it boot more reliably without the plug-in modules ?
Trim it back to the bare basics ( flashing LED, TV Text or something ) then when you have reliable re-booting start adding things.
Post Edited (hippy) : 4/12/2008 6:23:27 PM GMT
i just looked up the protoboard schematic. they use 10uF as filter cap for the 3.3V. so i will change my 100uF to 10uF and try again. If i watch the 3.3V with my scope, it takes appr. 1/2 second for the 3.3V to come fully up.
this boot problem occurs also without any plug-in modules , just a simple led flashing.
I just changed the cap to 10uF, i think its even worse.I can now wait only 2 minutes and the prop doesnt boot anymore.Cycling the power switch once more and it always worked.
I also tried with no 3.3V filter cap at all. Thats worst case;boots every second time only.
From what I can tell there is nothing fried about the Prop however an old 24C256 datasheet lists the minimum high input voltage as 0.7VCC which is around 3.5V. RTM, basically the 24C is not compatible with prop logic levels and the OP is simply trying to fit a square peg in a round hole because that's what he's got. No need to bang out our brains for that. Not very helpful I know but he just has to get the right chip or fudge some kind of level shifter (ugghh).
*Peter*
*Peter*
P.S. Glad to see someone picked up one of those cheap TV displays, wish it was VGA though.
*Peter*
Put a 3V3 Eeprom in and make sure the hardware is reliable before buggering about trying to use the 5V Eeprom. Otherwise you don't know what problem you are battling; is there something fundamentally screwed with your circuit implementation or is it just an issue with 5V Eeproms.
i got your message (however buggering has some bad meanings in german language, i think you didnt mean it that way (Scheisskerl,Sodomie, Analverkehr and other bad things)
Will ty to order Monday 3.3V dip devices. I have followed the thread "5 Volt devices to the prop" , but if the 24C256 is really only a sink device, what caused my 3.3 voltage going up to 4.2 volts ??
but my last append has been filtered out (my german google translation didn´t get through the filter for the word "buggering", some bad words after translation)
Will try to order Monday 3.3V dip devices. I have followed the thread "5 Volt devices to the prop" , but if the 24C256 is really only a sink device, what caused my 3.3 voltage going up to 4.2 volts ??
The problem with interfacing from +5V levels that rely upon current limiting is that the input voltage is clamped by the substrate diode to +3.3V. That means that a small amount of current will flow to the prop's supply rail which is not a problem as long as there is sufficient load on the supply to absorb this current otherwise the voltage will
rise. This happens at reset when the prop is in standby or any other time when it is drawing mininmal power. The voltage rises until some internal structure breaks down and
clamps the voltage (around +4V). This may be non-destructive but what is temporarily breaking down and does it affect the operation of the prop? Who knows.
Quick solution: Add a 1K (or less) resistor between the +3.3V rail and ground, at least to test this out.
Another VDD clamp that I use is simply two red leds in series with a 47R resistor. The leds act as excellent low-voltage zeners as LV zeners are too sloppy for this.
As Hippy mentioned it is good to check your circuit with the real devices, but once you do that why would you use the 24C version again?
*Peter*
P.S. "buggered" is a common Aussie/English expression for something that's stuffed (i.e. broken). It is perhaps a word we should not use because of it's proper meaning.
"Buggering about", in UK terms, would probably best translate as fruitlessly expending energy in a direction that was not the one which would best achieve the desired results.
Now I'm going out to find a *** and come home with sticky buns - a cigarette and sugar coated cakes
rgds,
John T
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'Necessity is the mother of invention'