Hi to all, can anyone tell me why to use the external resistors (one of the PSoC's pin is assigned for that)?
on what base does that pin is chosen & how does its presence or absence affects the operations.
Thanks & Regards-
The I2C bus is an open drain connection which allows all particpants to pull down the signal without interfering with each other. The resistors are needed to
- setting the impendance of the bus according to bus capacitance
- providing logical high on the bus-signals
1. you mean setting the impedance of the SDA &SCL buses, do they have variable capacitances; if they do what are the parameters affecting their capacitance.
2. I didn't get you, please elaborate 2nd point.
1) Every pin has an input capacity and a wire / pcb trace has got one also. You have to sum up all involved capacities and use your wanted frequency to calculate the required R which must be kept within the pecs limit. A usual approach was afair something like 5K.
2) An open drain bus has no device that can drive the signal to high-level, it only can be pulled low. So a resistor to Vcc is needed to generate a logic high on the bus.
Hi Bob, your explaination guides me towards the Pull-up Drive mode in PSoC.
After connection of the resistor, does it work in the same way as pull-up drive mode.
Whether the R is in PSOC or External (on an open drain configuration) the
basic functionality the same. However the tolerance of the internal PSOC
R is quite high, it varies a lot. 3.5K to 8.5 K for a PSOC 4.
Attached an ap note on calculating I2C pullup R's.
will go through the note & get back for further help.
Hi guys, what will be the effect if I change the parameter in I2Cs-
Slave addr----from 4 to 8
also what is the use & importance of the BRIDGE CONTROL PANEL?
How to interface & use it?
"what will be the effect if I change the parameter in I2Cs-Slave addr----from 4 to 8"
Just the same as if you move with your houshold two flats up the street: Your post will not arrive because you are living now at a different address.
I asked you before but you did not respond: What is the device you use as Master? Link to datasheet? How do you specify the address of the slave at master's side?
Sorry Bob, I'm using the Designer 5.4 & prog1.
In that still I do not know what to & how to use anything as a master. I'm just following the std. code doing modifications in that only. but as I have read it (I'm not sure)in my board I don't have access to master. do I have one? if I do then please guide me.
can we use the bridge as a master, I don't know much of the bridge controll panel. explain all.
Thnaks & Regards-