Verdin Development Board Errata
Toradex AG lEbenaustrasse 10 l 6048 Horw l Switzerland l +41 41 500 48 00 l
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Errata #5:
HAR-6600 – Ethernet PHY address strapping resistor for configuring
PHYAD2 missing
Affected Version:
Verdin Development Board V1.0B
Fixed in:
Verdin Development Board V1.1A
5.1
Customer Impact
In combination with the Verdin iMX8M Plus, the Ethernet PHY on the carrier board (which is
connected to the RGMII interface of the SoM) gets strapped to address 0b00011 rather than the
intended 0b00111. This address is not compatible with the default address configuration used in
applicable Toradex software, causing the 2nd Ethernet interface of the carrier board to be non-
functional. The strapped value and the resulting PHY address may be different in combination with
future Verdin modules.
5.2
Description
The last three bits of the PHY address are strapped by the PHYAD0, PHYAD1, and PHYAD2 pin.
PHYAD0 and PHYAD1 are located on the LED output signals, which are strapped correctly.
PHYAD2 is located on the RXC pin of the PHY (ETH_2_RGMII_RXC signal). The strapping resistors
R188 and R189 are both missing in the BOM. Intended by design is to strap the signal high by
assembling R188. Since both strapping resistors are missing, the strapping value is dictated by the
module's behavior of the ETH_2_RGMII_RXC signal during the enabling of the Ethernet power rails.
The Ethernet power rails are enabled on the carrier board by the PWR_CTRL_4 signal.
The Verdin iMX8M Plus has a weak pull-down enabled on the ETH_2_RGMII_RXC by default.
Therefore, the PHY address gets strapped to 0b00011 rather than the intended 0b00111. In this
case, the module can only communicate over the MDIO interface with the PHY if the driver
changes the address to 0b00011.
5.3
Workaround
The best workaround is to populate R188 with a 10k
Ω
resistor. The resistor is a 0603 type.
Figure 2. Verdin Development Board
– location of R188 (Top Side)
