LPC Microcontrollers中的主题 Re: LPC43xx GPIO clock source and speed

LPC43xx GPIO clock source and speed

lpcware — Wed, 15 Jun 2016 18:45:48 GMT

Content originally posted in LPCWare by openehs@gmail.com on Sat Apr 19 13:09:05 MST 2014
Hi,

I've been looking to change the clock source for GPIO (Port 7 on LPC4357) and change the speed but can't find the correct procedure. I can't find the relevant data in the datasheet.
Any help would be welcome.

Thx in advance

Johan

Re: LPC43xx GPIO clock source and speed

lpcware — Wed, 15 Jun 2016 18:45:49 GMT

Content originally posted in LPCWare by Pacman on Mon Apr 21 13:34:51 MST 2014
I believe I'll have to disappoint you, because to my understanding, the GPIO clock is wired directly to the M4 core clock.

In the UM10503, look at table 152 and table 154.
Table 154 refers to table 159 and table 162; both shows the config/status registers available; those registers do not allow you to change the speed.

What kind of frequency do you need ?

Re: LPC43xx GPIO clock source and speed

lpcware — Wed, 15 Jun 2016 18:45:49 GMT

Content originally posted in LPCWare by openehs@gmail.com on Mon Apr 21 14:46:13 MST 2014
Hi Packman,

That's what I was thinking, problem is that my coreclock is running on 180MHz (i've read this value back in debug mode) and when i'm toggle a pin via the not function I get a frequency of +-5MHz (Measured with Textronic TDS3034). because of this result I posted my question.
The problem is that I need to achieve a frequency of minimum 10Mhz for the interfacing

Regards

Johan

Re: LPC43xx GPIO clock source and speed

lpcware — Wed, 15 Jun 2016 18:45:50 GMT

Content originally posted in LPCWare by Pacman on Mon Apr 21 16:00:20 MST 2014
Hi Johan.

I think that 10MHz stable frequency can be archieved.
I've been able to set up the DMA to transfer a little more than 11MHz.

I posted source code for this a while back:

http://www.lpcware.com/content/forum/lpc4337-cant-get-dma-started

-You might find it useful.