[PD] Sensors GPIO Raspberry Pi Pd

Julian Brooks jbeezez at gmail.com
Fri Apr 19 20:51:10 CEST 2013


Hi Martin,

Meant to add re setting baud rate:
I've been making use of the gpio utility that comes with wiringPi
https://projects.drogon.net/raspberry-pi/wiringpi/the-gpio-utility/
Very handy for getting a quick visualisation of the current state of all
the pins and also easy-access to setting the baud rate too (amongst other
stuff).

Julian


On 19 April 2013 14:36, Martin Peach <martin.peach at sympatico.ca> wrote:

> Hi Julian,
> Yes I've been messing with coding it in c on the pi and sending the data
> to a [netreceive] in a Pd patch on another machine. I'm attaching the
> source code for the pi part and the Pd patch.
> The code can be compiled on the pi with
> gcc -o hello hello.c
> You need to set the IP address of the receiving machine in the code (I
> have 192.168.2.15, it could be 127.0.0.1 for the same machine).
> I tried changing the baud rate with
> sudo modprobe -r i2c_bcm2708
> sudo modprobe i2c)bcn2708 baudrate=90000
> but it works fine at the default 100000.
> It seems that you only need to write the command once, after that simply
> reading gets you another packet. Using a combined write/read operation only
> works half the time, as I also found on the Arduino. All you need to do is
> write the 0x4C command once, wait a millisecond or so and then read it.
> Another issue is that I tried this with the 8X1 sensor, not the 4X4 one,
> so the code reads 19 bytes (need to change the expected read size in the
> code). The 4X4 sensor sends 35 bytes which is 3 more than the i2c driver
> maximum, so you may not get the last part of a packet.
> I'll try it later with a 4X4 sensor to see what happens.
>
> Martin
>
>
> On 2013-04-19 07:01, Julian Brooks wrote:
>
>> Hi Martin,
>>
>> Did you manage to make any progress with the sensor on the Pi?
>> I also wanted to ask whether the output we're receiving from i2cdump
>> makes any sense to you as it doesn't to us currently?  Tried searching
>> around for possible info on the 'XX' & 'ff' but drawing a blank here.
>>
>> Cheers,
>>
>> Julian
>>
>>
>> On 13 April 2013 01:11, Julian Brooks <jbeezez at gmail.com
>> <mailto:jbeezez at gmail.com>> wrote:
>>
>>     Hey all,
>>
>>     Some success finally:
>>
>>     Hurrah!!
>>
>>     The scl breakout pin on the pi proto plate wasn't working properly.
>>
>>     When unscrewed halfway it works, when fully screwed in it doesn't.
>>
>>     So - now got this:
>>
>>     i2cdetect -y 0
>>
>>     0 1 2 3 4 5 6 7 8 9 a b c d e f
>>
>>     00: -- -- -- -- -- -- -- 0a -- -- -- -- --
>>
>>     10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>
>>     20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>
>>     30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>
>>     40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>
>>     50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>
>>     60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>>
>>     70: -- -- -- -- -- -- -- --
>>
>>     and
>>
>>     i2cdump -y 0 0xa
>>     No size specified (using byte-data access)
>>
>>     Gives a whole host of stuff I don't yet understand but I don't care
>>     currently as something is actually happening.
>>
>>     Will figure out a way of saving the console info (any hints
>>     anyone?)  as it gets badly mangled when cutting and pasting  but
>>     basically something like this:
>>
>>     i2cdump -y 0 0xa
>>     No size specified (using byte-data access)
>>           0  1  2  3  4  5  6  7  8  9  a  b  c  d  e
>>     f                      0123456789abcdef
>>     00: ff XX XX XX XX XX XX ff XX XX XX XX ff ff ff XX
>>  .XXXXXX.XXXX...X
>>     10: XX ff XX XX XX XX XX ff XX ff XX ff XX XX ff XX
>>  X.XXXXX.X.X.XX.X
>>     20: ff XX XX ff XX XX ff XX XX XX XX ff XX XX XX ff
>>  .XX.XX.XXXX.XXX.
>>     30: XX ff XX ff XX XX XX XX ff ff ff XX XX XX XX XX
>>  X.X.XXXX...XXXXX
>>     40: XX XX XX ff XX ff XX XX XX 64 XX XX d5 XX XX ff
>>  XXX.X.XXXdXX?XX.
>>     50: XX ff XX XX XX XX XX XX XX ff XX XX ff XX XX XX
>>  X.XXXXXXX.XX.XXX
>>     60: ff XX XX XX ff XX XX XX XX XX XX XX XX ff XX XX
>>  .XXX.XXXXXXXX.XX
>>     70: XX XX XX XX XX XX XX ff XX XX XX XX XX XX XX XX
>>  XXXXXXX.XXXXXXXX
>>     80: XX ff XX XX ff ff XX XX XX ff XX XX XX XX XX XX
>>  X.XX..XXX.XXXXXX
>>     90: XX XX ff XX XX ff XX ff XX ff ff XX XX ff ff XX
>>  XX.XX.X.X..XX..X
>>     a0: XX ff XX XX ff XX XX XX XX XX XX XX XX XX ff XX
>>  X.XX.XXXXXXXXX.X
>>     b0: XX XX ff XX XX XX ff XX XX ff XX XX XX XX XX XX
>>  XX.XXX.XX.XXXXXX
>>     c0: XX XX XX XX ff XX XX ff ff XX XX ff ff XX XX XX
>>  XXXX.XX..XX..XXX
>>     d0: XX XX XX XX XX ff XX ff XX XX XX XX XX ff XX ff
>>  XXXXX.X.XXXXX.X.
>>     e0: XX XX XX ff XX ff XX XX XX XX XX XX XX XX ff XX
>>  XXX.X.XXXXXXXX.X
>>     f0: ff XX ff ff XX XX XX XX XX XX XX XX XX XX ff XX
>>  .X..XXXXXXXXXX.X
>>
>>
>>     Progress at least.
>>
>>     Cheers,
>>
>>     Julian
>>
>>
>>
>>
>>
>>
>>
>>     On 12 April 2013 11:27, Julian Brooks <jbeezez at gmail.com
>>     <mailto:jbeezez at gmail.com>> wrote:
>>
>>         Message resent for thread archives with smaller picture size.
>>
>>         Julian
>>
>>         ---------- Forwarded message ----------
>>         From: *Julian Brooks* <jbeezez at gmail.com <mailto:
>> jbeezez at gmail.com>>
>>         Date: 11 April 2013 19:24
>>         Subject: Re: [PD] Sensors GPIO Raspberry Pi Pd
>>         To: Martin Peach <martin.peach at sympatico.ca
>>         <mailto:martin.peach@**sympatico.ca <martin.peach at sympatico.ca>>>
>>         Cc: PD List <pd-list at iem.at <mailto:pd-list at iem.at>>
>>
>>
>>         Hey Martin / list,
>>
>>         Finally got all the stuff and ...
>>
>>         It’s not working!
>>
>>         We spent the day soldering cables and connecting stuff up as per
>>         the Omron ‘App Note 01’ spec sheet.
>>
>>         Started off super-conservative using the  I2C level converter
>>         (case 3 page 4) http://www.adafruit.com/**
>> products/757#Blog/Flickr<http://www.adafruit.com/products/757#Blog/Flickr>
>>
>>         We tried resistors on both sides (being super paranoid!) and
>>         then we took  the low (Pi) side ones off.
>>
>>         We then moved on to case 2 page 3 of this same document…
>>
>>         At each stage we checked with “I2Cdetect –Y 1” and nothing was
>>         visible.
>>
>>         The grid shows no attached devices every time we run it.
>>
>>         We re-booted at every stage following the various online
>>         tutorials/methods of setting up I2C GPIO on the Pi (checked &
>>         double checked).
>>
>>
>>         As you can see we’re using a pi protoplate:
>>
>>         https://www.adafruit.com/**products/801<https://www.adafruit.com/products/801>
>>
>>         In the photo I’ve attached the cables are coded as follows:
>>
>>         Orange           GND
>>
>>         Yellow            5v
>>
>>         Blue                SCL
>>
>>         Green             SDA
>>
>>         The white is also 5v for the pull up resistors.
>>
>>         The resistor values are 4.7k btw.
>>
>>         We have tested the cable that terminates at the sensor and all
>>         that is OK.
>>
>>         I put a multimeter on the GND and SDA solder points on the
>>         sensor itself and got 3.7v…
>>
>>         I put a multimeter on the GND and SCL solder points on the
>>         sensor itself and got 0.0v…
>>
>>         Don’t know if this means anything or could be useful to know!
>>
>>         Stuck and frustrated now but hey, 3 weeks ago I knew absolutely
>>         bugger all about any of this and now I do (sort of).
>>
>>         I'm thinking we could do with the most basic i2c sensor we can
>>         find as we have nothing to compare.
>>
>>         Tonight I'm going to d/l a fresh raspbian and start from scratch
>>         to check that end.
>>
>>         Feel like if we can't get past the 'i2c-tools' tests we're
>>         screwed - never mind getting it in and out of Pd.
>>
>>         Any thoughts/pointers/options from anyone will be really
>>         appreciated?
>>
>>
>>         Cheers,
>>
>>
>>         Julian
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>
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