8-bit Microcontrollers中的主题 Warning: USB Module Is Designed To Function At Bus Clock Frequency = 24 MHz

Warning: USB Module Is Designed To Function At Bus Clock Frequency = 24 MHz

RedInVan — Sun, 31 Jan 2010 11:07:40 GMT

Warning: USB Module Is Designed To Function At Bus Clock Frequency = 24 MHz

Hello, First of all, I am so new to the Microcontollers' designs and using tools for te purpose of designing them. So be patient with me. Right now I am using CodeWarrier 6.1 to write a code for MC9S08JM60 in Processor Expert mode. I get the above warning message even if all the CPU and USB settings are in default values(i.e.without touching any settings). I tried to change the bus frequency, but I get out of range error. Here is the related settings on the CPU:

High Speed Mode:

High speed clock: Internal Clock
Bus frequency divider: Auto Select
Internal Bus Clock: 16.0 MHz

Fixed frequency clock: 0.015625 MHz

It is truly appreciated if someone help me to know what I am doing wrong and how to fix the problem. Also, the project is attached for your reference.

Regards

Re: Warning: USB Module Is Designed To Function At Bus Clock Frequency = 24 MHz

pgo — Sun, 31 Jan 2010 20:46:41 GMT

Dear RedInVan,

The MC9S08JM60 is intended to be used with an external crystal for USB operation. 4 or 12 MHz would be typical with a 24MHz internal bus frequency. The internal clock would not have the required accuracy.

You should be able to configure the clock appropriately using Processor Expect.

bye

Re: Warning: USB Module Is Designed To Function At Bus Clock Frequency = 24 MHz

RedInVan — Tue, 02 Feb 2010 04:38:49 GMT

Thank you so much. As you see I am no expert in the field of Micros. Again I do appreciate your help.

Regards