Problem with I2C Comunication
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Posts: 46,084
Hello Srs....
I am working in a big proyect with 12 MAX6955 (Display Driver (16
7-Segment))with comunication I2C) and a Basic Stamp Bs2p24.... I have
already the 17 circuit board (12 Slave and one Master)... And i placed in
each board one power suply (5Vdc LM7805).. I use to comunicate this boards
a Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL) to comunicate
each board with the other board , Please see the bad diagram
O----O----O----O----O----O----O----O----0----O----O----O
¡
@
O = Slave Board (One MAX6955 with One Power Supply)
---- = Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL)
@ = Master Board (One Bs2p24 with One Power Supply)
OK.. I use the GND conductor to reference Power Supply...
My Problem is follow:
When I turn on the system.. I can't see any information in the any
7-Segment,
When i was cheking this board i found right, i tried to connect only one
slave to one master and i can find the same problem..... Please see this
diagram (O---@)
When i tried any solution i tried to conect this two board in the same
power supply and i can found this two board is right, very right..... then
i connected in the same example to conneced gnd of power suply 1 to gnd of
power suply 2 and 5Vdc of power suply 1 to 5VDC of power suply 2 and i can
find this working good....
Anyone know.... why don't it run with only Gnd reference? and it need to
connect all the power supply in parallel
I appreciate your prompt response
Best regards
Eng. Damian Trujillo G.
Venezuela, Caracas
I am working in a big proyect with 12 MAX6955 (Display Driver (16
7-Segment))with comunication I2C) and a Basic Stamp Bs2p24.... I have
already the 17 circuit board (12 Slave and one Master)... And i placed in
each board one power suply (5Vdc LM7805).. I use to comunicate this boards
a Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL) to comunicate
each board with the other board , Please see the bad diagram
O----O----O----O----O----O----O----O----0----O----O----O
¡
@
O = Slave Board (One MAX6955 with One Power Supply)
---- = Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL)
@ = Master Board (One Bs2p24 with One Power Supply)
OK.. I use the GND conductor to reference Power Supply...
My Problem is follow:
When I turn on the system.. I can't see any information in the any
7-Segment,
When i was cheking this board i found right, i tried to connect only one
slave to one master and i can find the same problem..... Please see this
diagram (O---@)
When i tried any solution i tried to conect this two board in the same
power supply and i can found this two board is right, very right..... then
i connected in the same example to conneced gnd of power suply 1 to gnd of
power suply 2 and 5Vdc of power suply 1 to 5VDC of power suply 2 and i can
find this working good....
Anyone know.... why don't it run with only Gnd reference? and it need to
connect all the power supply in parallel
I appreciate your prompt response
Best regards
Eng. Damian Trujillo G.
Venezuela, Caracas
Comments
over any great distance. I thought it was
for same-board multiple-IC interconnects.
It looks like you use the ground pins to
tie your signal grounds together -- normally
a good thing -- but this hasn't worked.
When you tie your +5 together also, it works.
I'd check how far apart the +5 volts are
on the various boards. I'd also check
current in your ground wire. Something is
giving you a voltage shift which is
messing you up.
--- In basicstamps@yahoogroups.com, "dtrujillo_riese@c..."
<dtrujillo_riese@c...> wrote:
> Hello Srs....
>
> I am working in a big proyect with 12 MAX6955 (Display Driver (16
> 7-Segment))with comunication I2C) and a Basic Stamp Bs2p24.... I
have
> already the 17 circuit board (12 Slave and one Master)... And i
placed in
> each board one power suply (5Vdc LM7805).. I use to comunicate this
boards
> a Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL) to
comunicate
> each board with the other board , Please see the bad diagram
> O----O----O----O----O----O----O----O----0----O----O----O
> ¡
> @
> O = Slave Board (One MAX6955 with One Power Supply)
> ---- = Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL)
> @ = Master Board (One Bs2p24 with One Power Supply)
>
> OK.. I use the GND conductor to reference Power Supply...
>
> My Problem is follow:
>
> When I turn on the system.. I can't see any information in the any
> 7-Segment,
>
> When i was cheking this board i found right, i tried to connect
only one
> slave to one master and i can find the same problem..... Please see
this
> diagram (O---@)
>
> When i tried any solution i tried to conect this two board in the
same
> power supply and i can found this two board is right, very
right..... then
> i connected in the same example to conneced gnd of power suply 1 to
gnd of
> power suply 2 and 5Vdc of power suply 1 to 5VDC of power suply 2
and i can
> find this working good....
>
> Anyone know.... why don't it run with only Gnd reference? and it
need to
> connect all the power supply in parallel
>
> I appreciate your prompt response
>
> Best regards
>
> Eng. Damian Trujillo G.
> Venezuela, Caracas
Thank you but see it
I put only two board (O---@) conected to cable 8 inches very near... And i
put two computer power supply one to the master and one to the slave (5VDC
with oned cable GND to reference).... And it don't work... If i add one
cable between 5Vdc to `Power Supply 1 with 5Vdc to `Power Supply 2 IT
WORK.... I don't understand.... DO you understand.... This is very rearly
Help me please....
Eng. Damian Trujillo
Venezuela, Caracas
Mensaje Original
De: Allan Lane [noparse]/noparse][url=http://forums.parallaxinc.com/group/basicstamps/post?postID=d127dtRDSrdkjc5dRhXmj4DB7NadETTQixJhJW5KHeh6vMt928iWHNqfBivqoCbmU2vb1-7XDrZwNeClg_aMvnar]allan.lane@h...[/url
Para: basicstamps@yahoogroups.com [noparse]/noparse][url=http://forums.parallaxinc.com/group/basicstamps/post?postID=y5IohVvshVw-DAT7gdRS3lzWDOQTdpOOxocmjhFzkATZJ5N5e5h4zm3oY788QX2tk7onuim0FBtuhGAM9AmU_cg]basicstamps@yahoogroups.com[/url
Cc:
Asunto: [noparse][[/noparse]basicstamps] Re: Problem with I2C Comunication
Fecha: 29/09/2003 14:54:55
Mensaje:
I didn't think I2C was designed to go
over any great distance. I thought it was
for same-board multiple-IC interconnects.
It looks like you use the ground pins to
tie your signal grounds together -- normally
a good thing -- but this hasn't worked.
When you tie your +5 together also, it works.
I'd check how far apart the +5 volts are
on the various boards. I'd also check
current in your ground wire. Something is
giving you a voltage shift which is
messing you up.
--- In basicstamps@yahoogroups.com, "dtrujillo_riese@c..."
<dtrujillo_riese@c...> wrote:
> Hello Srs....
>
> I am working in a big proyect with 12 MAX6955 (Display Driver (16
> 7-Segment))with comunication I2C) and a Basic Stamp Bs2p24.... I
have
> already the 17 circuit board (12 Slave and one Master)... And i
placed in
> each board one power suply (5Vdc LM7805).. I use to comunicate this
boards
> a Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL) to
comunicate
> each board with the other board , Please see the bad diagram
> O----O----O----O----O----O----O----O----0----O----O----O
> ¡
> @
> O = Slave Board (One MAX6955 with One Power Supply)
> ---- = Flat Flex Cable with four (4) conductor (GND,SDA,GND,SCL)
> @ = Master Board (One Bs2p24 with One Power Supply)
>
> OK.. I use the GND conductor to reference Power Supply...
>
> My Problem is follow:
>
> When I turn on the system.. I can't see any information in the any
> 7-Segment,
>
> When i was cheking this board i found right, i tried to connect
only one
> slave to one master and i can find the same problem..... Please see
this
> diagram (O---@)
>
> When i tried any solution i tried to conect this two board in the
same
> power supply and i can found this two board is right, very
right..... then
> i connected in the same example to conneced gnd of power suply 1 to
gnd of
> power suply 2 and 5Vdc of power suply 1 to 5VDC of power suply 2
and i can
> find this working good....
>
> Anyone know.... why don't it run with only Gnd reference? and it
need to
> connect all the power supply in parallel
>
> I appreciate your prompt response
>
> Best regards
>
> Eng. Damian Trujillo G.
> Venezuela, Caracas
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>Dear Allan
>
>Thank you but see it
>
>I put only two board (O---@) conected to cable 8 inches very near... And i
>put two computer power supply one to the master and one to the slave (5VDC
>with oned cable GND to reference).... And it don't work... If i add one
>cable between 5Vdc to `Power Supply 1 with 5Vdc to `Power Supply 2 IT
>WORK.... I don't understand.... DO you understand.... This is very rearly
>
>Help me please....
>
>Eng. Damian Trujillo
>Venezuela, Caracas
Damian -
Have you included a 4.7K pull-up resistor between Vdd and SDA as well as from
Vdd and SCL. The Stamp will not work without these, per the Stamp Manual.
Also, if you are using I2CIN or I2COUT you are limited to the pins you may
use to connect to the I2C Bus. You MUST use either 0/1 or 8/9 to connect to
the I2C Bus.
I hope that helps.
Regards,
Bruce Bates