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Messages - david_f

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1
NXPTM LPC2XXX and LPC17XX / Re: LPC2388 & KSZ8721 10Mbit problem
« on: September 24, 2009, 10:20:54 AM »
Hello !

Ok, I finally found something : I forced the pins TXD2, TXD3 and TXEN to the ground, put 2 pull-down 1K resistors (pin 11 = RX_ER and pin 9 = E_CRSDV) and disconnected pins 22 = E_CRS and pin 9 = E_CRSDV, leaving pin 22 floating. I also use a GPIO pin from the LPC to make a hard-reset (pin 48 = PHY_RST). In LPC side, I setup EMAC pins in the PINSEL register first and then apply a hard reset. I think the pull-down resistors helps to setup the straping options properly, I don't know...

Finally, my boards seems to work with these modifications  :P

However, I've no explanation about the Olimex modifications... Mark, did you have any issue in Half duplex mode with your Olimex board ? The misalignement can be explained by this.

Thanks again !

Best Regards,
David

2
NXPTM LPC2XXX and LPC17XX / Re: LPC2388 & KSZ8721 10Mbit problem
« on: September 23, 2009, 11:38:54 AM »
Hi Mark !

Ah ah, it is interesting ! This means the board and the schematics are differents. I've some problems to receive packets correctly on my design (new PCB) which is based on the schematics (LPC2378-STK). The Micrel PHY is a KSZ8721BL set up in RMII mode as well. To get some boards working, I have to connect a strap between pin 9 & 22. If I remove it, I reveive no packet at all. However, some boards doesn't work even if I connect these pins together : an error from the status descriptors for each packet received (bad length or alignement error or CRC error). When I read the buffer, I have 12/13 first-bytes of a packet correctly (example for an ARP packet : 6 bytes broadcast (0xFF) followed by 6 bytes of my source MAC address (my computer) and then... dummy bytes...). No problem to send packets though, checked with ethereal.

I received an email from Micrel yesterday :

We think the problem may be due to the strap between pins 9 & 22.

For RMII mode (see datasheet) the E_CRS signal (on customer schematic)
should connect to pin 9 RXDV/CRSDV and not pin 22 CRS. This needs to be
corrected as we believe this is the cause of the receive errors
(misalignment).
 
We suspect in the modification that you strapped pin 9 and pin 22
together but also cut pin 22. Pins 9 & 22 are both outputs so you do not
want them connected together (you may be lucky in RMII but certainly we
would not advise connecting the two pins).


Well OK, but it doesn't work... why ? The schematics provided by Micrel attached to the email are all designed for MII (pin 22 and pin 9 are used separetly), not RMII...

To conclude : there is something wrong either in the datasheet or with this chip in RMII mode, or with my PCB design... no reply from Olimex too... I made a small test code to check EMAC. Does someone write another one for LPC2388/78 + Micrel PHY ?

Thanks again Mark,

Best Degards,
David

3
NXPTM LPC2XXX and LPC17XX / Re: LPC2388 & KSZ8721 10Mbit problem
« on: September 20, 2009, 07:15:20 PM »
Hi Mark,

I've seen your message in the Sparkfun forum today, thank you very much your help !

Yes, I saw nothing as well on my board until I decided to remove the part. The best way would be to check with a simple multimeter (when I removed the part, I didn't know where to search). I've received no reply from Olimex unfortunately. I contacted a Micrel FAE (here in France) last week, I'll transmit the schematics. He told me that this part (KS8721) is very mature and he should send me some designs quickly.

I'll ket you know about this strange issue,

Thanks again for your help.

Best Regards
David

4
NXPTM LPC2XXX and LPC17XX / Re: LPC2388 & KSZ8721 10Mbit problem
« on: September 11, 2009, 12:57:33 PM »
Hi Mark,

I wondered if you have few minutes to check if theses 2 pins are not connected together on your Olimex board. On mine, there is a small wire below the chip that I found out when I soldered the chip out. I don't understand why we need to connect these 2 pins together, the datasheet provides no explanation.

Many thanks in advance,

David




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