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by Hi-Z
Sat Nov 22, 2014 8:04 pm
Forum: General discussion
Topic: resize Pi SD Card
Replies: 5
Views: 1627

Re: resize Pi SD Card

I will add to this thread as I recently migrated from a model B to a B+ and in the process found out my new micro SD card (B+) had less space on it that my original SD card (B). Credit should be given to FrozenCow for providing me with the needed background to perform this task REF: http://softwareb...
by Hi-Z
Wed Oct 01, 2014 8:12 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

Pretend you're in a large room with many other people. You can talk to them and them to you. During the conversations you find out that you are actually on the 33rd floor of a building and rumour has it that there may be others on the hiding out on the 50th floor but there is no way to talk to them....
by Hi-Z
Wed Oct 01, 2014 6:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

1) The quickest & easiest solution

2) Ideally, you would use a i2c voltage level shifter between the RPi (3v3) and the RTC (4v5) when they are powered from different sources as you suggest .... hence the SDA & SCL of the RTC would not connect directly to the RPi as they would in scenario 1.
by Hi-Z
Wed Oct 01, 2014 3:21 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

Having multiple pull up resistors on the SDA & SCL lines isn't really an issue unless you have lots and lots of them (yielding lower overall parallel resistance resulting in greater current draw) or the power supplies are of different voltages (ie RPi at 3.3V and RTC at 5V) In this case, it appears ...
by Hi-Z
Sat Aug 24, 2013 6:10 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

Thanks for confirming this ... Myself and those reading this thread in the future appreciate your input

Have fun with the 1-wire devices, I found that they present their own set of challenges with timing and reliability of data transfer because they use "bit-banging" instead of the i2c protocol.
by Hi-Z
Sat Aug 24, 2013 1:00 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

Playing with the hardware only seems drastic when you already have an alternate solution. In this case, playing with the hardware helped to isolate the root cause ... I'm really surprised it took 5 months before someone figured out how to do the same in software. Anyways, nice find and a good share....
by Hi-Z
Sat Mar 16, 2013 6:43 pm
Forum: Other projects
Topic: Raspberry Control - Control RPi with your Android Device
Replies: 31
Views: 29841

Re: Raspberry Control - Control RPi with your Android Device

I was excited to try this out but unfortunately Google Play states it's incompatible with my Samsung Galaxy S (first generation SGH I896/7) and won't allow the download. On a side note, I guess I could research on how to force the install by bypassing the Play store entirely. If possible, would you ...
by Hi-Z
Mon Mar 04, 2013 10:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

Funny, I don't remember ever having to set that bit when I first got my device ... even found the reference in the datasheet and it didn't ring a bell. I can't give you a direct answer but I will save your hours of possible frustration :D No matter what command you send to talk to the RTC, it will f...
by Hi-Z
Sun Feb 24, 2013 9:06 pm
Forum: Wanted
Topic: WANTED: MicroUSB Pigtails!
Replies: 6
Views: 4283

Re: WANTED: MicroUSB Pigtails!

I ended up buying a USB A/B cable off ebay for less than a dollar and cutting it in half.

It's cheaper (and simplier) to do this than actually buying just one connector
by Hi-Z
Sat Feb 23, 2013 3:09 pm
Forum: Troubleshooting
Topic: EEPROM not writing or reading (fully)
Replies: 4
Views: 2124

Re: EEPROM not writing or reading (fully)

It should compile without issues. It's been so long since I first installed it that I can't remember the exact details, but I do remember it was simple, easy and caused me no grief. Recheck to make sure i2c is installed properly (it probably is, but the basis of of troubleshooting is to elimate what...
by Hi-Z
Fri Feb 22, 2013 5:49 pm
Forum: Troubleshooting
Topic: EEPROM not writing or reading (fully)
Replies: 4
Views: 2124

Re: EEPROM not writing or reading (fully)

The 24c16 uses 8 bit addressing while the 24c64 uses 16 bit addressing. Also, the 24c16 and smaller address memory blocks via bus addresses 0x50 -> 0x57 while the 24c32 and larger address it all via 0x50 I don't know what software you are using for read/write but this is where you need to tell it. I...
by Hi-Z
Sun Feb 17, 2013 5:06 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4256

Re: RTC using P5 header

To clarify the previous post: If the pull up resistors are connected to 5 volts then connecting directly to the (3v3) GPIO pins is bad. If the pull up resistors are connected to 3v3 then connecting to the GPIO pins is ok. A level converter is still recommended to prevent accidentally applying the wr...
by Hi-Z
Sun Feb 17, 2013 4:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4256

Re: RTC using P5 header

I can't find an actual schematic for this board though. This should be what you are looking for http://www.emartee.com/Attachment.php?name=42059.pdf @poing The RTC is a 5 volt device and the RPi is 3v3 on the GPIO pins. If you connect the RTC directly to GPIO pins then there is the possibility of c...
by Hi-Z
Sun Feb 17, 2013 3:56 pm
Forum: General discussion
Topic: EEPROM/Microcontroller Programmer
Replies: 6
Views: 1863

Re: EEPROM/Microcontroller Programmer

eeproms, such as the 24HCxx series, use the i2c bus to communicate. There's lots of info on this already and it's easy to use.

Programming the microcontroller is another issue. Depending on the variety, they can be programmed different ways. More details are needed
by Hi-Z
Tue Feb 12, 2013 3:44 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Invert GPIO RxD pin (solved)
Replies: 26
Views: 16554

Re: Invert GPIO RxD pin

Yes using the 74HC04 (but not the HCT04) will work, if you power it with 3V3. But you must not input more than 3V3 to the input of the 74HC04, so the RxD signal from the energy meter should be a 3V3 level. A 74HC04 that is powered by 3v3 will work just fine with TTL (0~5v) signal levels as an input...
by Hi-Z
Tue Feb 12, 2013 3:26 pm
Forum: General programming discussion
Topic: giving recognition in programming code
Replies: 4
Views: 1013

Re: giving recognition in programming code

If you're going to use any part of someones code then the honourable thing to do is give them credit.

If it was working code snippet ... Portions of code taken from John Doe

If it was an example of bad code ... Modified code taken from John Doe
by Hi-Z
Fri Feb 08, 2013 8:07 pm
Forum: General discussion
Topic: PiUPS?
Replies: 6
Views: 1924

Re: PiUPS?

One more thing .... Car batteries are 13.6 volts not 12 volts as would be expected
by Hi-Z
Fri Feb 08, 2013 8:03 pm
Forum: General discussion
Topic: PiUPS?
Replies: 6
Views: 1924

Re: PiUPS?

a picture is worth a thousand words ... see attached my 1000 word essay :lol: Instead of monitoring for 0 volts (ie car turned off), you should start your shutdown when the input voltage has started to drop instead. I drew a resistor divider in the attached file, but that really doesn't explain it p...
by Hi-Z
Fri Feb 08, 2013 5:47 pm
Forum: General discussion
Topic: PiUPS?
Replies: 6
Views: 1924

Re: PiUPS?

Some 12V cigarette lighter outlets are on continuously while others are enabled when the key is turned. If you have more than one outlet in your vehicle, then this might be a quick and dirty solution. When working with automotive applications, one should always consider using a 'quench' diode from t...
by Hi-Z
Sun Jan 27, 2013 4:11 pm
Forum: Python
Topic: Raspberry Pi and 74HC595 shift registers the easiest way
Replies: 9
Views: 6266

Re: Raspberry Pi and 74HC595 shift registers the easiest way

Nice .... it reminds me of the time I designed a flash memory programmer using a computers parallel port to output and then shift registers to load the sequence. One thing that might be useful is a routine to load and entire byte and output that to the registers, because that's generally what people...
by Hi-Z
Fri Jan 25, 2013 6:36 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

But you got me thinking about how it is with updating time in RTC. Ahh ... my evil plan to get others to think is working :twisted: From the various testing I've done, I believe the fake-hwclock saves its time on shut down. Might be good to take a look at that code and see how it's done there and a...
by Hi-Z
Thu Jan 24, 2013 11:14 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Tutorial: Add a Real Time Clock to the Raspberry Pi
Replies: 113
Views: 128763

Re: Tutorial: Add a Real Time Clock to the Raspberry Pi

Here's my 'hack' to get the RTC to load properly at boot or use the NTP server. First off ... I'll assume everyone has taken the 2 steps to get the module correctly loaded: rtc-ds1307 .... added to /etc/modules echo ds1307 0x68 > /sys/class/i2c-adapters/i2c-1/new_device .... added to /etc/rc.local A...
by Hi-Z
Thu Jan 24, 2013 10:08 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Generating a regular clock
Replies: 3
Views: 904

Re: Generating a regular clock

The DS1307 real time clock has a square wave output which can be set to 32.768 kHz
by Hi-Z
Thu Jan 24, 2013 9:58 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 38kHz modulation with GPIO output??
Replies: 6
Views: 3797

Re: 38kHz modulation with GPIO output??

I can't figure out if you're trying to make a 38kHz clock signal or a modulated 38kHz signal, so I don't know if this will help. The DS1307 Real Time Clock (RTC) has an programmable output square wave which can be configured for 1 Hz, 4.096 kHz, 8.192 kHz and 32.768 kHz Note: If you have the RTC int...
by Hi-Z
Thu Jan 24, 2013 9:24 pm
Forum: Other projects
Topic: Flash EEPROM programmer
Replies: 21
Views: 30005

Re: Flash EEPROM programmer

Is this flashrom tool able to program normal EEPROMs like 24LCxx in buses like SPI, I2C and Microwire ?? For 24xx16 devices and smaller, i2c-tools & smbus are more than adequate. For 24xx32 and larger, the device addressing goes from 8 bit to 16 bit, of which the above tools may have some issues. e...

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