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by SlowBro
Wed Nov 08, 2017 3:48 pm
Forum: Beginners
Topic: Why does i2cdump from an EEPROM show different data each time I run it?
Replies: 2
Views: 1061

Re: Why does i2cdump from an EEPROM show different data each time I run it?

I found a workaround. It's not Python, but it is consistent, and I can wrap it in Python. Used this 24C* EEPROM reading software (if that link goes bad I mirrored it here ) and I can write then read a string back. [email protected]:~/eeprog-0.7.6-tear12# echo "This is a test" | ./eeprog -16 -f -q -w ...
by SlowBro
Wed Nov 08, 2017 3:24 pm
Forum: Beginners
Topic: Why does i2cdump from an EEPROM show different data each time I run it?
Replies: 2
Views: 1061

Re: Why does i2cdump from an EEPROM show different data each time I run it?

I found that with EEPROMs the address does shift but I don't know how to control that. Seems like it's good behavior for automatically reading a page at a time, but I need to be able to read data consistently each time. Somebody know?
https://www.i2c-bus.org/auto-increment/
by SlowBro
Wed Nov 08, 2017 5:31 am
Forum: Beginners
Topic: Why does i2cdump from an EEPROM show different data each time I run it?
Replies: 2
Views: 1061

Why does i2cdump from an EEPROM show different data each time I run it?

When I run i2cdump against my AT24C256B twice, first is blank data and second is the data I stored. Then and only then can I use my Python script to read the EEPROM. Why is this behavior? Some kind of internal pointer in the EEPROM that needs to be reset, maybe with i2c.seek(0)? [email protected]:~# ...
by SlowBro
Sat Nov 04, 2017 2:05 pm
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

What are your stats for SD failures?
by SlowBro
Sat Nov 04, 2017 2:27 am
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

It’s a very cool SDK. Does it work out of the box with Amazon AWS, especially their IoT and server management capabilities? I appreciate that their AWS server management for example can directly manage my Raspbian instance as though it were one of their cloud servers. Also I don’t see how Nard compl...
by SlowBro
Sun Oct 29, 2017 10:24 pm
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

So using SD cards is a feature not a bug. Grin. I will have my config on EEPROM and if the customer’s card fails I’ll overnight them a new one and if they swap it, it should come right up. @Heater have you ever had a failure after editing boot files on your bench? I found some relatively inexpensive...
by SlowBro
Sun Oct 29, 2017 3:38 pm
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

Right so for a device deployed in the field it sounds as though you would use another device such as the C.H.I.P. which boots from onboard NAND. I see that the Pi can boot from NAND in theory but not in practice. Another consideration is to use industrial strength and/or rugged SDs such as which hav...
by SlowBro
Sun Oct 29, 2017 2:34 am
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

It all depends on what you want to do and what failure rate you can tolerate. The 80/20 rule sounds great. Until you have a 100 units installed in remote locations and 20 of them are going to fail prematurely and it costs you a thousand bucks to visit each one and fix it. I don't have that situatio...
by SlowBro
Sun Oct 29, 2017 2:00 am
Forum: Advanced users
Topic: Mount I2C flash filesystem?
Replies: 1
Views: 1458

Re: Mount I2C flash filesystem?

Update: It hadn't occurred to me to Google Pi I2C EEPROM. Found this . I can write a text string and read it back. So likely what I will do is read my config files into memory as a Python dict, write that out as one large JSON, then when I need to retrieve them I can read them back, write the config...
by SlowBro
Sun Oct 29, 2017 1:56 am
Forum: Advanced users
Topic: Mount I2C flash filesystem?
Replies: 1
Views: 1458

Mount I2C flash filesystem?

I'm wanting to make my SD card read-only and add an external I2C flash such as one of these for storing a few small config files. My config files are 5-6KB but I want a bit of room to grow hence I want a filesystem with at least 64KB/512KBit of room. OS is Raspbian Stretch Lite. I know this is typic...
by SlowBro
Fri Oct 27, 2017 5:33 pm
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

Well eventual failure is one thing but the concerns are of the rapid decline of relatively new cards. Mounting read-only clearly must improve the odds, as has been reported in various places. On a hunch I checked the TinyCore forums to see what they see on corruption. As you probably know their OS i...
by SlowBro
Fri Oct 27, 2017 10:31 am
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

So it sounds as though you’re saying that corruption can occur even without a power loss? Just daily writing.
by SlowBro
Wed Oct 25, 2017 11:47 am
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

Heater wrote:
Wed Oct 25, 2017 10:03 am
External, obviously. Could be a tiny USB memory stick. Whatever storage medium you like.
Not obviously. The Pi can interface on its I2C, SPI, or SDIO interfaces :-) I've pondered adding extra storage via a custom cape using one of those interfaces, which is why I asked.
by SlowBro
Wed Oct 25, 2017 9:22 am
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

Thanks. So when you say you put it on a different device you mean an external usb drive or something else?
by SlowBro
Tue Oct 24, 2017 9:59 pm
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

TimG wrote:
Tue Oct 24, 2017 1:38 pm
The read/write partition should be created aligned with the allocation group size (typically 4MiB).
Anyone know how to do that? Couldn’t find instructions in the link.
by SlowBro
Tue Oct 24, 2017 11:18 am
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 195
Views: 97079

Re: Raspbian with Read-only Root

I think if you ever write anything to the SD card you are defeating the point of making this read-only root system. Even if you make a new partition to write data to. The SD card knows nothing about your partitions and file systems it only knows about blocks of data. If it's going to screw up, whic...
by SlowBro
Mon Oct 23, 2017 10:02 am
Forum: Advanced users
Topic: [SOLVED] Can I setup an AP with SSL without Internet access?
Replies: 6
Views: 2191

Re: [SOLVED] Can I setup an AP with SSL without Internet access?

Turns out I was only getting the error for http:// (non-SSL) forms on Windows Firefox ESR 52.4.0 (32-bit). When I tried an iPhone (iOS 11.0.2) and Android (4.4.2) I didn't get any errors on the form. So for now, it is sufficient to leave the connection unencrypted. I did configure hostapd as WPA2 so...
by SlowBro
Mon Oct 23, 2017 9:00 am
Forum: Automation, sensing and robotics
Topic: Can I make This? Door Automation;
Replies: 3
Views: 562

Re: Can I make This? Door Automation;

Happy to help best I can, but please outline more of your requirements. What exactly do you need to device to do? I gather you want it to lock and unlock the door from the inside with a push button, is that right?
by SlowBro
Mon Oct 23, 2017 12:09 am
Forum: Automation, sensing and robotics
Topic: Can I make This? Door Automation;
Replies: 3
Views: 562

Re: Can I make This? Door Automation;

I've no experience with it but it doesn't sound as though you require any Pi at all? Maybe a large button connected to a relay?
by SlowBro
Sat Oct 21, 2017 8:37 pm
Forum: Advanced users
Topic: [SOLVED] Can I setup an AP with SSL without Internet access?
Replies: 6
Views: 2191

Re: Can I setup an AP with SSL without Internet access?

That’s good news. Another problem: I can’t issue a cert to a device with a private IP. How can I work around this?
by SlowBro
Sat Oct 21, 2017 12:06 pm
Forum: Advanced users
Topic: Speed up Raspbian boot
Replies: 10
Views: 11721

Re: Speed up Raspbian boot

If it’s a machine controller does it ever need to shut down? I had a goal of battery power but decided to let that go. Mine is on 24x7, although I plan to include solar and battery as an option, so I may revisit boot optimization. Likely I will switch to Tiny/Arch/Buildroot/Yocto if I do that.
by SlowBro
Sat Oct 21, 2017 11:49 am
Forum: Advanced users
Topic: Speed up Raspbian boot
Replies: 10
Views: 11721

Re: Speed up Raspbian boot

SurferTim wrote:
Sat Oct 21, 2017 11:17 am
I boot into Stretch/Pixel desktop in 17 seconds. Edit: with a RPi3.

I checked with a PNY Prime uSD, and it boots in 18 seconds.
Ok I'm on a B+ so there's that. OP said he is using everything.
by SlowBro
Sat Oct 21, 2017 11:14 am
Forum: Advanced users
Topic: Speed up Raspbian boot
Replies: 10
Views: 11721

Re: Speed up Raspbian boot

SurferTim wrote:
Sat Oct 21, 2017 11:10 am
This is the easiest way to improve boot time.
SlowBro wrote:
Sat Oct 21, 2017 3:57 am
I do have a very fast sd card though.
I use SanDisk Ultra Plus uSD cards. Boots in a hurry.
Samsung Evo+ boots in about 30 secs on a stock build of stretch lite. What about yours?
by SlowBro
Sat Oct 21, 2017 11:08 am
Forum: Advanced users
Topic: Speed up Raspbian boot
Replies: 10
Views: 11721

Re: Speed up Raspbian boot

That doesn’t sound right. There’s only one image for Tiny Core and it’s said to work with all processors. http://www.tinycorelinux.net/9.x/armv6/releases/RPi/ As I was saying I don’t have a direct answer to your question but another possibility: Make your users realize the system is doing something,...
by SlowBro
Sat Oct 21, 2017 10:16 am
Forum: Advanced users
Topic: [SOLVED] Can I setup an AP with SSL without Internet access?
Replies: 6
Views: 2191

Re: Can I setup an AP with SSL without Internet access?

I thought of doing the latter but how would the phone validate the cert without internet?

Oh wait — the phone probably would use the cell network to validate. Let me try it and see.

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