LPC11C24 On chip can-bus problem.

[lpcware]

Content originally posted in LPCWare by Ahmet_B on Thu Aug 02 04:03:55 MST 2012
Hi everybody.

I try to use on chip can-bus module of LPC11C24. But i can't achive to use it. I tried 3 examples code of LPCXpresso (can,can_onchip,canopen_onchip) but none of them worked. I give you schematic of mine board.

[IMG]http://img502.imageshack.us/img502/8613/scheman.jpg[/IMG]



When i looked CanH and CanL pins i couldn't see anything in these pins. Does anybody have any idea why it doesn't work?

Thanks everybody.

[lpcware]

Content originally posted in LPCWare by Ahmet_B on Thu Aug 02 08:01:50 MST 2012
Thank you for your support Zero. It works. :)

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Thu Aug 02 07:12:59 MST 2012

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Quote: Ahmet_B
Zero, are you sure to connect 5v supply to pin 20.

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I'm sure :cool:

I know you can't believe that :)

EA is showing how to connect LPC11C24: http://www.embeddedartists.com/sites/default/files/docs/schematics/LPCXpressoLPC11C24revB.pdf

Sheet 5: Pin 20 - VCC is connected to PSU_VBUSX, which is USB VBUS (Sheet 2) via Schottky :eek:

Datasheet LPC11Cx2/Cx4: 32-bit ARM Cortex-M0 microcontroller; 16/32 kB flash, 8 kB SRAM; C_CAN Rev. 3 — 27 June 2011

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Quote:

9.2 C_CAN on-chip, high-speed transceiver characteristics
Table 8. Static characteristics
...
Supply; pin VCC
[COLOR=Red]VCC supply voltage 4.5 - 5.5 V[/COLOR]

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[lpcware]

Content originally posted in LPCWare by Ahmet_B on Thu Aug 02 06:45:11 MST 2012
Zero, are you sure to connect 5v supply to pin 20. Because i connect there 3.3v, because it is Vcc. Additionaly i connect 5v supply to pin 17. Am i wrong?

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Thu Aug 02 05:08:00 MST 2012
This chips (11C2x) need 5V supply at Pin 20 = VCC to supply it's CAN transceiver :eek:

So you need also a 5V voltage for your 3.3V Chip :mad::mad:

Please don't ask me why NXP isn't using a 3.3V transceiver, I don't understand that :rolleyes:

(And that's the reason why I'm using 11C14 with external 3.3V transceiver from Texas Instruments for real 3.3V boards)