Author Topic: Amstrad CPC WiFi  (Read 329959 times)

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Offline CraigsBar

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Re: Amstrad CPC WiFi
« Reply #1775 on: 17:51, 05 September 17 »
Awesome, thanks next time I catch up with my c64 gurus cpc tall key I'll Polish the connector again

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Offline pelrun

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Re: Amstrad CPC WiFi
« Reply #1776 on: 13:37, 08 September 17 »
I've been having major crashing problems with my CPC for ages now. After a *lot* of mucking around, I figured out it doesn't happen when the M4 doesn't start up the wifi (e.g. I pull the sd card out so it starts up unconfigured). External power didn't help at all. Happens less when the M4 is the only thing connected to the expansion port, but when it's in the MotherX4 it's no good.

I've done some other projects personally using the ESP8266, and in those I've invariably had a large capacitor across the 8266's power pins to make them start reliably. The M4 doesn't have such a capacitor, only a small decoupling cap. Adding a 100uF electrolytic across the pads on the back of the board has made it rock solid much better than it was.
« Last Edit: 14:45, 09 September 17 by pelrun »

Offline pelrun

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Re: Amstrad CPC WiFi
« Reply #1777 on: 11:18, 09 September 17 »
Now that I can use my m4 again, can I suggest using the configured M4 NetBIOS name to set the esp8266 hostname? My dhcp server registers hostnames into the local dns, but the m4 only shows up as the default "ESP_xxxxx", and there's rather a few of those already on my network :)

Offline ||C|-|E||

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Re: Amstrad CPC WiFi
« Reply #1778 on: 12:57, 09 September 17 »
I've been having major crashing problems with my CPC for ages now. After a *lot* of mucking around, I figured out it doesn't happen when the M4 doesn't start up the wifi (e.g. I pull the sd card out so it starts up unconfigured). External power didn't help at all. Happens less when the M4 is the only thing connected to the expansion port, but when it's in the MotherX4 it's no good.

I've done some other projects personally using the ESP8266, and in those I've invariably had a large capacitor across the 8266's power pins to make them start reliably. The M4 doesn't have such a capacitor, only a small decoupling cap. Adding a 100uF electrolytic across the pads on the back of the board has made it rock solid.

Thanks, that was very interesting to read and definitely a super-simple mod  :)

Offline CraigsBar

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Re: Amstrad CPC WiFi
« Reply #1779 on: 13:33, 09 September 17 »
I've been having major crashing problems with my CPC for ages now. After a *lot* of mucking around, I figured out it doesn't happen when the M4 doesn't start up the wifi (e.g. I pull the sd card out so it starts up unconfigured). External power didn't help at all. Happens less when the M4 is the only thing connected to the expansion port, but when it's in the MotherX4 it's no good.

I've done some other projects personally using the ESP8266, and in those I've invariably had a large capacitor across the 8266's power pins to make them start reliably. The M4 doesn't have such a capacitor, only a small decoupling cap. Adding a 100uF electrolytic across the pads on the back of the board has made it rock solid.
Which way round is the cap?

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Offline pelrun

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Re: Amstrad CPC WiFi
« Reply #1780 on: 14:46, 09 September 17 »
Positive is on the right of the photo, next to C14.

Offline CraigsBar

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Re: Amstrad CPC WiFi
« Reply #1781 on: 14:41, 10 September 17 »
Positive is on the right of the photo, next to C14.


Thanks. Applied. Lets see how it goes....
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Offline GUNHED

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Re: Amstrad CPC WiFi
« Reply #1782 on: 15:42, 10 September 17 »
Should this modification be applied to every M4 card, or is it needed only in few circumstances?
http://futureos.de --> Get the revolutionary FutureOS (Recent update: 2019.08.07)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2019.08.14)

Offline CraigsBar

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Re: Amstrad CPC WiFi
« Reply #1783 on: 16:20, 10 September 17 »
Should this modification be applied to every M4 card, or is it needed only in few circumstances?
I am just seeing if it helps with stability on my cpc 6128.

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Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1784 on: 19:17, 10 September 17 »
Should this modification be applied to every M4 card, or is it needed only in few circumstances?
Only if you have stability problems. I guess it will depend on your powersupply if it can deliver the small bursts when wifi is transmitting fast enough. There's already a 10uF cap on the power of the wifi and a 0.1uF on the wifi board itself. I for one don't have that issue testing with multiple power supplies.
That being said I have read of plenty of people having issues with ESP8266 rebooting in other projects, the normal fix is a 10uF-100uF cap.

Offline pelrun

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Re: Amstrad CPC WiFi
« Reply #1785 on: 21:21, 10 September 17 »
It's not exclusively a powersupply issue. I've tried several, *and* my lab bench supply to no avail. I've also gone through and minimised the voltage drops everywhere else in my setup (including a 0.2v drop in my 6128's power switch - the internal contacts were dark brown with 30 years of gunk!)

It's simply too far away from the 8266, and a local 10uF is too small to handle the fast 400mA current spikes the 8266 generates at startup.

Also, 8266 modules are notoriously variable, and what might work fine on one unit can be completely inadequate on another. Realistically you need at least 47uF near the module (and that's in addition to the 0.1uF-10uF ceramic decoupling cap, you need both) to cope with the different sensitivities of individual modules.

Offline pelrun

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Re: Amstrad CPC WiFi
« Reply #1786 on: 21:56, 10 September 17 »
One other thing I've just thought of to check - there's an LDO regulator (AMS1117) on the board to supply the needed 3.3v rail, and these regulators generally *require* a tantalum or electrolytic cap on the output in order to prevent the regulator from oscillating. The M4 is using a ceramic cap there instead. Unfortunately, ceramics aren't appropriate for this because they've got negligible ESR (and this is one of the few places you actually *need* some ESR.) There are regulators that are designed to work with a ceramic output cap, but this isn't one of them.


A big transient spike (for instance when the 8266 starts up) could be causing the regulator to ring really badly. I guess I need to break out the oscilloscope...



http://www.ti.com/lit/an/slva115/slva115.pdf
« Last Edit: 21:59, 10 September 17 by pelrun »

Offline RobertM

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Re: Amstrad CPC WiFi
« Reply #1787 on: 00:05, 11 September 17 »
Ah that makes a lot of sense.

I had one power supply, USB PlugPack / WallWort that had a higher current rating and didn't work. Only half the HTTP page would send then stop.

I haven't had a good look at the schematic but two things come to mind -

1) As mentioned, a large cap (100uF or so) across the ESP8266 as these can have very high peak currents.

2) I will always use a high precision 3.6 Volt regulator when mixing 3.3v chips with 5v chips as it improves the noise margin dramatically - most 3v3 chips are fine to run at 3v6 but check the specs.

Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1788 on: 05:58, 11 September 17 »
One other thing I've just thought of to check - there's an LDO regulator (AMS1117) on the board to supply the needed 3.3v rail, and these regulators generally *require* a tantalum or electrolytic cap on the output in order to prevent the regulator from oscillating. The M4 is using a ceramic cap there instead. Unfortunately, ceramics aren't appropriate for this because they've got negligible ESR (and this is one of the few places you actually *need* some ESR.) There are regulators that are designed to work with a ceramic output cap, but this isn't one of them.
Actually some AMS1117 datasheets say that you can use ceramic, ie:
http://www.szjzsic.com/upfile/AMS1117.pdf
Obviously the 1117 on M4 is a clone of some sort and the safer choice would have been a 22uF tant.  So you may be right, depending on the clone 1117 specs.
I later replaced the LDO with a  AP2114H due to the drop-voltage of the AMS1117 that could pose a problem when used in MX4. The AP2114 datasheet also states it can use ceramics.

Offline RobertM

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Re: Amstrad CPC WiFi
« Reply #1789 on: 08:33, 11 September 17 »
I thought these boards were hand soldered???

Ceramics often fracture and fail if hand soldered.

Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1790 on: 09:07, 11 September 17 »
I thought these boards were hand soldered???

Ceramics often fracture and fail if hand soldered.

All SMD components are put on with a tweezer into the solder paste, then baked in the reflow oven.
Only hand soldering is connectors (+esp module on older boards) and removing solder bridges after reflowing.

Btw. here is a few examples of ldo boards with AMS1117 all using ceramics, so either newer versions of the AMS1117 only needs very low ESR or all the designs are bad, being fully possible.



Offline Bryce

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Re: Amstrad CPC WiFi
« Reply #1791 on: 09:53, 11 September 17 »
Using a tantalum capacitor is the recommendation, in order to improve the quality of the output, however the part will work with any capacitor at the output, it just won't be as good. The manufacturers of those cheap 1117 boards don't care how good the output is and know that their standard customer for this type of board doesn't have the knowledge to know better either, so they slap on whatever was on offer at the local Shenzen market.
When a datasheet says "required", that usually  means "required to achieve the values we claimed above", not necessarily required to get the part working.

Bryce.

Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1792 on: 10:04, 11 September 17 »
Using a tantalum capacitor is the recommendation, in order to improve the quality of the output, however the part will work with any capacitor at the output, it just won't be as good. The manufacturers of those cheap 1117 boards don't care how good the output is and know that their standard customer for this type of board doesn't have the knowledge to know better either, so they slap on whatever was on offer at the local Shenzen market.
When a datasheet says "required", that usually  means "required to achieve the values we claimed above", not necessarily required to get the part working.
Yup I get that and I should have used a tantalum being on the safe side because buying a bunch of 1117's from China I have no clue of the manufacturer and what its exact specs is.

Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1793 on: 10:17, 11 September 17 »
I am pondering to add the 100uF cap for future boards.
From the feedback I have had very few people had issues with their boards (out of 320)  aside from the usual "edge connector" needs cleaning and in some cases a faulty board (dodgy connection, loose microsd slot, broken power switch or esp8266 flash going wonk).
Every board is tested for about 20-30 minutes with micro sd and wifi before I ship it off.
But if it can help in some cases, why not, it will only look a bit silly with the piggy back :)

Offline AlexD

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Re: Amstrad CPC WiFi
« Reply #1794 on: 16:06, 11 September 17 »
Don't know about this hardware patch but what I read may explain why I encounter some problems with my m4 wifi.
I get some disconnections (while using SymIRC but also wget, even on small file size). This happen after "a certain time" which is variable but tend to lower whith time (e.g. when I try wget first attempt are downloading more packets that the second when etc.)
Should I try to add a capacitor ?

Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1795 on: 17:40, 11 September 17 »
Don't know about this hardware patch but what I read may explain why I encounter some problems with my m4 wifi.
I get some disconnections (while using SymIRC but also wget, even on small file size). This happen after "a certain time" which is variable but tend to lower whith time (e.g. when I try wget first attempt are downloading more packets that the second when etc.)
Should I try to add a capacitor ?
I doubt it's your problem. Because if the ESP8266 crashes the CPC would eventually lockup when the M4 tries to get more data from it (in fact I should make it reboot the ESP if it times out, something to do sometime). - You can also check if the web interface is still there, if it is, the ESP isn't crashed.
But sure worth a try, if you have a 100uF cap handy, your result would be interesting.

Offline AlexD

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Re: Amstrad CPC WiFi
« Reply #1796 on: 18:15, 11 September 17 »
Indeed it is probably not crashed as I can trigger a wget command again.
Will try to find a capacitor to test it

Offline villain

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Re: Amstrad CPC WiFi
« Reply #1797 on: 20:41, 11 September 17 »


...with their boards (out of 320)


You really sold 320 boards? Absolutely impressive and for sure the most succesful piece of hardware after the CPC's commercial era. Congrats! ;-)

Offline Duke

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Re: Amstrad CPC WiFi
« Reply #1798 on: 21:09, 11 September 17 »

You really sold 320 boards? Absolutely impressive and for sure the most succesful piece of hardware after the CPC's commercial era. Congrats! ;-)
Thanks - Actually 332, but only 320 shipped. A few more weekends...

There is probably other boards that have done just aswell or better, like C4CPC, XMEM and MX4.

Offline Bryce

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Re: Amstrad CPC WiFi
« Reply #1799 on: 10:14, 12 September 17 »

You really sold 320 boards? Absolutely impressive and for sure the most succesful piece of hardware after the CPC's commercial era. Congrats! ;-)

Not sure about the most successful bit. The MegaFlash sold around 370 and I'm sure some of TotOs boards may have sold more.

Bryce.
« Last Edit: 10:17, 12 September 17 by Bryce »