CCS/LAUNCHXL2-RM57L: Do we need to connect the external resistance connection for EMAC RXD Pins?

Saravanakumar S93

Part Number: LAUNCHXL2-RM57L
Other Parts Discussed in Thread: RM57L843

Tool/software: Code Composer Studio

Hi All,
We are using RM57L843 microcontroller. We are not using TMS570 based microcontroller.
e2e.ti.com/.../785415

    #As mentioned in the above link, Do we need to modify the Launchpad board with below external resistance settings ?
            CRS=2.2K External Pullup resistance with 3.3V.It is available in Launchpad XL2 RM57 board itself.
            RX_ER=2.2K External Pullup resistance with 3.3V.It is available in Launchpad XL2 RM57 board itself.
            RX_DV=2.2K External Pulldown resistance with ground.It is available in Launchpad XL2 RM57 board itself.
            RXD[3]=2.2K External Pulldown resistance with ground
            RXD[2]=2.2K External Pulldown resistance with ground
            RXD[1]=There is no external resistance required
            RXD[0]=There is no external resistance required
            COL=There is no external resistance required

#There is no Test point (or) Pin out available for RXD[2], RXD[3] in the Launchpad XL2 RM57 board. How do we connect the external resistance?

#For RM57L843 Microcontroller, inorder to make the Ethernet example program working, Which is the VCLK4 frequency needs to be set? (40MHz (or) 75MHz (or) Both the frequencies OK?)

Regards,
S.Saravanakumar

over 4 years ago

0 QJ Wang over 4 years ago

TI__Guru**** 198766 points

Hello,

The VCLKA4_DIV is used for the EMAC internal logic. But the transmit and receiver clock source are provided by the external ethernet PHY. The VCLKA4_DIV can be 37.5, 40, 75, or other valid value.

The pull-up and pull-down resistors are determined by the PHY's strap options. Please check PHY datasheet.

0 Saravanakumar S93 over 4 years ago in reply to QJ Wang

Expert 1300 points

Hi QJ Wang,

Already, you have checked the PHY datasheet and given the below proposal.

"Does your proposed solution valid (or) not with respect to the resistance? Please find the attached screenshot for the same. Link is available in the initial post.

Regards,

S.Saravanakumar

0 QJ Wang over 4 years ago in reply to Saravanakumar S93

TI__Guru**** 198766 points

Yes, the proposal is correct.

0 Saravanakumar S93 over 4 years ago in reply to QJ Wang

Expert 1300 points

As per your proposal, Do we need to add the below external resistance in Launchpad XL2-RM57 board?

RXD[3]=2.2K External Pulldown resistance with ground
RXD[2]=2.2K External Pulldown resistance with ground

Because, there is no external resistance available in Launchpad XL2-RM57 board for RXD[3], RXD[2] pins.

Regards,

S.Saravanakumar

0 QJ Wang over 4 years ago in reply to Saravanakumar S93

TI__Guru**** 198766 points

Hello,

I just checked the RM57 device datasheet. The RXD[3:2] has internal pull-down. The DP836x also has internal pull-down for RXD[3:2]. So the external pull-down resistors are not required.

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CCS/LAUNCHXL2-RM57L: Do we need to connect the external resistance connection for EMAC RXD Pins?