ENET uDMA and Descriptors

[matthewdowsett]

Hi,

I am using the TWR-K60N512 and the TWR-SER modules. My project is a CAN to Ethernet bridge bare-metal system.

Using the drivers provided by Freescale I am reasonably sure I have the ENET configured correctly. Also can take a register dump from the PHY and the contents look OK cross checking with the KSZ8041 Datasheet. When I connect the provided Ethernet cable to my PC I get both green LEDs active, with one LED flashing each time my PC sends an Ethernet packet (I am spying using MS Network Monitor).

I have hard coded a TX packet and called enet_transmit_packet function. So both TDAR and RDAR are set but no TX or RX events are occurring. The RX and TX descriptor ring buffers are never altered as I expect they would be.

My question is does the uDMA need any consideration? I am running a very simple bare metal system that has not touched the AIPS, DMA, etc.

Or any other tips would be greatly appreciated :-)

Matthew

[matthewdowsett · Accepted solution]

Hi,

Problem solved - the issue was in the MCG setup - a clocking issue. It appears that the uDMA does not need any consideration other than clearing the MPU CESR VLD bit.

Matthew

[Monica]

Matthew,

that's great, thanks for sharing the workaround with us!

You rock!

Best,

Monica.