MPC5748G - How to reduce startup time?

[xierxiaofeng]

Hello, 

      I am using MCP5748G. It takes about more than 100ms to work properly after powering up.  How many milliseconds is the normal startup time? How to reduce startup time?

Thanks!

[petervlna]

Hello,

Startup of device is defined in the datasheet:

petervlna_0-1737013356590.png

This is time when voltage is applied to the point where is device released from reset and can start executing code.

If you are referring to SW startup time, then this will of course vary on how good/optimized is your code written and what it all does and will vary on each customer application requirements.

In general, if you write it in ASM it will save you a lot of time.

Best regards,

Peter

[xierxiaofeng]

Hi Peter,
Thanks your reply. I measured the clock initialization time with an oscilloscope to be about 130ms, is this time normal? How to shorten the clock initialization time.

Best regards

[petervlna]

Hello,

I measured the clock initialization time with an oscilloscope to be about 130ms, is this time normal?

Well, since you are using some drivers which are based on platform and not optimized specially for this device, the time can be various. there will be huge overhead compared to ASM init code.

in reality, to setup clocks in shortest possible time would require approximately 100 instructions.

Please always refer to your driver documentation for execution time.

NXP usually release those in quality package of drivers.

It will also depends on how do you measure the execution time. Measuring with some driver toggling pin will be much different from tracing the instruction execution with advanced debuggers.

best regards,

Peter

[xierxiaofeng]

Hi Peter，
Thanks your replay.
Where to find driver doucment for execution time?Could you please provide ASM init code?

best regards,
xierxiaofeng

[petervlna]

Hello,

Where to find driver doucment for execution time?

Driver documentation is usually accompanied with driver. NXP has it either directly in the driver doc folder or in the quality package which is located at NXP SW account along with driver installation.

petervlna_1-1739433206285.png

Could you please provide ASM init code?

No. The point to write ASM code is to have it optimized for your application.

best regards,

Peter

[xierxiaofeng]

Init System Clcok图片.png图片.png

The execution time of three lines of code is about 130ms