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Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Wed Dec 19, 2012 10:22 pm
I have changed one more thing in comparision to pure svn trunk:
Code: Select all
Index: mcuconf.h
===================================================================
--- mcuconf.h (revision 4948)
+++ mcuconf.h (working copy)
@@ -45,7 +45,7 @@
#define STM32_CLOCK48_REQUIRED TRUE
#define STM32_SW STM32_SW_PLL
#define STM32_PLLSRC STM32_PLLSRC_HSE
-#define STM32_PLLM_VALUE 25
+#define STM32_PLLM_VALUE 8
#define STM32_PLLN_VALUE 336
#define STM32_PLLP_VALUE 2
#define STM32_PLLQ_VALUE 7
This is because STM32F4DISCOVERY board has 8k oscillator and the example was designed for olimex board.
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Wed Dec 19, 2012 10:49 pm
One more thing.
Please also note, that for bmsr I am also getting the value 1111111111111111 from time to time.
How can i change the clocks to be sure that it is the hardware problem, not software?
Thanks in advance!
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Wed Dec 19, 2012 11:39 pm
by Giovanni
If you get corrupted data from the PHY then it could be a problem of unstable electrical connection. The driver reads the corrupted value and does the wrong thing.
Giovanni
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Thu Dec 20, 2012 1:26 am
Hi Giovanni!
On the ethernet dovelopment post you wrote:
by Giovanni » Mon Mar 26, 2012 3:40 pm
Hardware discussions are absolutely welcome.
BTW, one of the ChibiOS customers created a control board based on the STM32F4-Discovery, it has the DP83848 in RMII mode clocked by a MCO. I should receive a sample soon and will be able to answer the question.
The only problem I see is that in order to generate 50MHz the MCU clock must be set to 150MHz.
Main is 168MHz. Maybe this is the reason of my problem?
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Thu Dec 20, 2012 2:11 am
by DeusExMachina
May be it is a hardware problem - use short wires for connections!
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Thu Dec 20, 2012 9:57 am
25cm. Too long? Will give it a try.
Greetings
Piotr
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Thu Dec 20, 2012 10:35 am
by iggarpe
You mean 25cm traces from STM32 to PHY or from PHY to ethernet transformer (usually integrated into the RJ45 connector) ?.
In either case, that may very well be your problem. You must be very careful with traces from PHY to transformer, and in fact you should be using an impedance controlled differential pair of traces and be careful not to cross ground planes and stuff like that. In the case of traces from STM32 to PHY, length matching could help, and some series resistor damping too. If this is the case, try placing a series 33 ohm resistor near each output signal pin.
Ethernet signals are much more tricky than MII/RMII, so if you cannot shorten the distance, always place the PHY as close as possible to the ethernet transformer and focus in MII/RMII signal integrity.
Anyway, 25cm is asking for trouble.
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Thu Dec 20, 2012 4:28 pm
OMG! Shortening the wires did the trick!
I would never guess that 25cm wires are way too long.
Code: Select all
--- 192.168.1.10 ping statistics ---
332 packets transmitted, 332 received, 0% packet loss, time 331002ms
HUGE thanks to all for your help
Greetings,
Piotr Klimczak
Re: STM32F4DISCOVERY and DP83848 Pocket loss at ~40%
Posted: Thu Dec 20, 2012 6:49 pm
by iggarpe
Glad to have helped !.
I bet your setup would have given nightmares to a signal integrity expert for months