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Two Microcontroller Design Process

kulkarnisanket47 , 04-21-2021, 11:59 AM
What are the best ways to design and decide pins for peripherals for a system with two controllers?
I am studying NXP Rapid IOT Kit design.
And tried to design the schematics from scratch. I am stuck at the controller's design as both controllers have more than 40 pins. I am not able to decide how to design a schematic without error. How can I decide peripherals by Excel or other means? Any articles or best practices?
qdrives , 04-22-2021, 12:16 PM
Is having more then 40 pins the difficulty?
Is the two MCUs the difficulty?

From what I can make of it, that systems has two MCUs - one application and one communication MCU. As both are an MCU, both can work independent.
That is also where you need to start to think - what peripheral is best suited for which task and therefor which MCU. Actually, the block diagram only shows SPI, UART and I2C to/from the communication MCU and status LEDs.
The biggest difficulty with such designs is that the application does not have direct 'connection' to the communication and the communication no access to process parameters. These have to be communicated between the two via SPI, UART or I2C. This is a software issue, not hardware.
kulkarnisanket47, 05-10-2021, 02:56 PM
Thank You Sir. Your suggestion made me think and I did some small project. And then I felt that I am lagging in reading the documents.
robertferanec , 04-23-2021, 05:08 AM
I do not know exactly what you are trying to do, however, if you are using something as a reference board, start with the pin assignment which would be the same as on the reference board (e.g. use the same pins for UART, I2C, etc). Use these pins to connect everything what you need and if you need more, then decide how to use the pins which you have not connected yet.

kulkarnisanket47, 05-10-2021, 02:53 PM
Yes sir Your suggestion helped me. I have worked as Firmware Developer before. Your suggestion helped me to recall that my Hardware manager uses to see the pin assignments in the IDE to see if which functionality is enabled or disabled. So I am trying to assign the pin first in IDE and if no errors are in the IDE pin assignment according to my timer and other peripheral requirement, I will finalize the pins assignment.
qdrives , 04-23-2021, 11:08 AM
@kulkarnisanket47 I already asked two questions and your comments makes me ask a bit more.
I am asking these questions as I do not know, like Robert, in what way to help you solve your problem. We are here to help, but sometimes the question is just not clear.
Let me deconstruct your comment...
- "The problem is I am not able to design the schematic ... by myself." So: no time, no tools, no knowledge, etc?
- "So how to design the schematic from scratch" This does seem to point to knowledge.
- "... with two microcontrollers". Well, I already asked and gave some pointers.
If you have little knowledge of electronics, then a project like this is way to complex. Better start with the more simple 28pin Arduino projects.
kulkarnisanket47, 05-10-2021, 02:49 PM
Thank You Sir. Your suggestion made me think and I did some small project. And then I felt that I am lagging in reading the documents.
kulkarnisanket47 , 05-10-2021, 01:56 PM
kulkarnisanket47 , 05-10-2021, 02:48 PM
I tried to find the answer but was unable to find the answer. I used to connect the hardware with me to supply to see maximum current and calculate power.
1. How to calculate the Power Rating or power consumption of Individual Modules or parts of PCB, Sleep mode, Active Mode before hardware development?
2. In my case, bcoz of two modes: Active and Sleep, How can I calculate board rating for power. In K64 Microcontroller there are IDDA, IDD_RUN, IDD_WAIT, IDD_VBAT, IUART(Page 14 of K64 Datasheet) and many more currents specified. Which current to consider for Power calculations?
3. Any resources to read. I have also added the datasheet of NXP K64.
kulkarnisanket47 , 05-10-2021, 02:59 PM
qdrives , 05-13-2021, 09:28 AM
I guess row "I" is skipped due to the reading difficulty. Read I, l and 1. Spot the difference? Same would go for O and 0.

Power consumption is not a quick calculation if low power is required. For normal operation I always take the highest power with all peripherals on.
Add pin currents if it maters (> 2mA per pin). Add current requirement for the other components too (memory, buffers, LEDs).
With low power, it is also the question to what level can you drop (how to reactivate). Peripheral in sleep? How about external circuits?
If the question is on power supply module, then I have never had it close (200mA PSM, 100mA load).

Better start a separate new question next time so more people will react.
kulkarnisanket47, 05-13-2021, 09:38 AM
Thank you Sir. For your answers.
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