RAM fails verify
Jonathan
Posts: 1,023
Hi All,
Got my new Prop boards. I forgot to order sockets for the Prop, so I just soldered it right to the board. All was well, hooked up some DS18B20's and was having fun. SOldered a few more components on and now the RAM refuses to verify. I can't swap the Prop out to test. Are there any possibilities other than a dead chip? Prop plug works fine on other Props.
Thanks!
Jonathan
Got my new Prop boards. I forgot to order sockets for the Prop, so I just soldered it right to the board. All was well, hooked up some DS18B20's and was having fun. SOldered a few more components on and now the RAM refuses to verify. I can't swap the Prop out to test. Are there any possibilities other than a dead chip? Prop plug works fine on other Props.
Thanks!
Jonathan
Comments
A picture of the board would help.
Robert
Thanks! I checked and indeed the voltage was a little low. I didn't have the vreg I needed so I am powering it through a couple of wires. I added a 100uF that I hadn't put in yet, and bingo, it works!
Thanks, made my day.
Jonathan
Get a regulator. Make sure you have both positive and both negative power pins of the Prop connected to the correct power rails. Use decoupling capacitors across both of those, 100nF say.
Don't worry.The regs show up on Wednesday. Just scabbing power from a breadboard till then. I had to know if the boards I had made worked. The board has all VDD and VSS pins connected and decouple cap across the power. I had a dodgey power connection and hadn't put the 100uF in yet.
Jonathan
Let's see some pics of your boards when they are finished...
Ideally at the input power end you should have a bulk capacitor (47+uF electrolytic), a 1-10uF Tantalum, and a 0.1uF (100nF) X7R mono preferred. If the 0.1uF and tantalum are at the end of the prop this will be OK but I would like another 0.1uF (depends on layout) at the other end. Since the EEPROM is a distance away from the prop it also needs its own 0.1uF.
Of course, my assumptions are based on what I perceive the pcb tracks to be since you have not posted a pic of this.
I do ahve a100uF on the input and place for a .1. No room for a tant or the decoupe near the eeprom. I can scab a decouple cap on the tracks of the EEPROM and maybe the tant on the inout. I'll chage the board for future runs. Thanks a lot for the advice! And I'll take as much as I can get.
Jonathan
Perhaps you can put the caps under the prop on the underside??
What are you using for the power supply?
Can you tell me more about your hydronic heating controller. I have a rather involved hydronic heat system for room heat and hot water but it is not uC controlled. It is however working fairly good but not quite what I would like.
Thanks
Aaron
effectively ineffective. Need to clean my screen now, was just drinking in that moment.
Wonderful.
Mike
If I can play on words to punch the point, I will
Aaron, the system is actually at my buddies house. There are a couple of solar thermal panels and a 220VAC, 7kW on demand heater. Pumps and such to suit. The controller runs the pump through the panles if there is heat to be had and if not uses the electric heater. Works very well and now we are adding an xbee and Pi to the system. If you have more questions feel free to ask. You can PM me if you like.
JOnathan
Thanks Jonathan.
The biggest problem w/ my system is a store bought room thermostat that just does not have enough settings and options (the line voltage ones seem to be that way). I really need to make a new one. Thought maybe that was part of your system.
Aaron
Indeed it is, no thermostat, just temp. sensors. And it is very flexible, as the system knows the time and date. It also has features like vacation mode. Very easy to do with a Prop/Stamp/SX and fun to boot!
Jonathan
I made a PROP program for fun something like that. It read 6 DS18B20 temp sensors, placed on various water pipes. An RTC triggered a record to an SD card, readable in MS Excell.
It wouldn't be hard to make a smart thermostat way better than what is commercially available for a custom system.
Aaron
Jonathan
Is the propeller itself broken or are there other possible causes? The crystal doesn't matter because the propeller is running in RCFAST mode during programming, I think.
I'm guessing that the one crystal I see is used by the top FPGA to deliver the clocks to the two? Prop chips? But I don't see the regulator(s) except for the unpopulated switcher up the top right. Have you checked for ripple by switching to AC on your meter or using a scope? I t may even be transients. I can't see where your programming header is unless it's shared with the 5-pin combicon and it doesn't look like it's X3 either.
The RAM checksum error should only come up after it loads RAM and before it programs EEPROM so that's why I'm guessing it's a regulation issue perhaps.
yes exactly. the clocks are driven by the FPGA. The 3.3V regulator is on the vertical plug in card at the top of the picture between the two electrolytic caps. I checked the voltage with the scope, there are short bursts of noise around 50mV, I guess from the switching regulator. I also changed the whole regulator board - no change.
The two props share one EEPROM so the second could probably disturb the first one while booting/programming. But I checked the cascaded reset signals. The second prop is properly held in reset while the first is programmed.
I got fed up (lazy) of putting a reg on the pcb every time. Then I plugged the wrong PSU onto it - Props, EEPROMs and SRAMs do not seem to pass the 9 Volt test (the SD card did (after it cooled down)).
I love to scrounge 1206 caps off of old PCBs and then stick them everywhere on the track side as near to the chips as poss. If there is a base under the DIP Prop then there would be space inside that for a Tant or two.
Alan