Hello.
I'm in the process of selecting a new processor for a project solving a simpe task (assumably). The main task for the MCU to be solved is simply:
1) It receives some data (it requests information, in I2C MASTER mode) from a peripheral device over I2C. 2) It converts that info to another datalayer-protocol, and sends it to another (requesting) MCU (now, I guess we must be in I2C SLAVE mode on another I2C port...).
We are currently using Keil uV4 IDE and do not want to switch IDE.
I will very much apreciate your answers to (some of) the following questions: Q-1: Can you recomment Cortex-M3 to this application (we prefer M3 over M0+) ? Q-2: Will it be problems (software-wise) using Cortex-M3 with two I2C ports/busses for solving this task? Q-3: I assume the one I2C must run in SLAVE mode, and the other I2C must run in MASTER mode ?
I couldn't find any C-code I2C drivers for Cortex-M5 "out there". Q-4: Does anybody know if there are (C-code) drivers or sample-code for I2C drivers for Cortex-M3 available (freeware or "paywere") ?
I'll appreciate assistance with these issues.
Best regards Terje Bøhler
Note that the Cortex-M3 is still basically a core. There are a number of manufacturers who have Cortex-M3-processors. And they have different peripherial support.
It's no problem running multiple I2C interfaces as long as the processor has them. NXP LPC17xx have three. But you can find others that just has two interfaces.
The actual code? Depends on which Cortex-M3 you select. But any Cortex-M3 with at least two I2C should be good enough.
Apart from using two I2Cs, you've given no information at all about the application. So we have no real basis for any recommendation - other than just ensuring that the number of simultaneously-usable I2C interfaces is >2.
I should imagine that the (vast) majority of Cortex-Mx devices have >2 I2Cs...
But the I2C has nothing to do with Cortex-M3 - or any other core - so there's no use asking for "I2C drivers for Cortex-M3"
The I2C will be specific to the particular chip or family or manufacturer; so the real question is, "What manufacturers provide drivers for their I2C implementation(s)" - and the answer would be, "just about all of them!"
That would depend entirely upon the things which connect to those I2Cs. Again, you've no information - so it's impossible to say!
You need to look at the specifications of the devices - that will tell you whether they are slaves or masters...
Thank you Per and Andy.
I really appreciate your comments. I'm not familiar with the I2C bus structure and we're in a process establishing both new uP, IDE etc (the entire ecosystem required for the development). First of all, I think the most important question I have to solve must be: Maybe a MULTIMASTER bus architecture is the best choice for my MCU/PCB (and, not what I originally thought, due to lack of knowledge - see my original post). My MCU is simply to: 1) Receive some data (on our request) from a SLAVE device (on the same PCB) over I2C (we are MASTER). 2) Send that data (modified) to another requesting MCU (external PCB) over I2C (we are SLAVE).
I just read the book "Mastering the I2C Bus" by Vincent Himpe, and it seems that my MCU probably should implement the I2C using one common I2C MULTIMASTER bus architecture: 1) The "SLAVE device" (acc to it's spec) is obvious in SLAVE mode. 2) Our MCU acts as a MASTER when requesting that (above) "SLAVE device" for data. 3) An external MCU is MASTER, requesting our MCU for data (we then act in SLAVE mode)
Q: What will be the best bus-structure for this application: a) one common I2C multimaster architecture or b) two separate I2C buses: - - one separate I2C bus from our MCU to the SLAVE device (on the same PCB) and - - another separate I2C from our MCU to the MASTER device (external PCB) ?
I appreciate your comments on this matter.
I'm not familiar with the I2C bus structure
easily fixed
I2C Specification: www.nxp.com/.../UM10204.pdf