SPEBlox long uses a the DP83TD510E, a 10BASE-T1L PHY that contains numerous configuration registers that can be useful for debugging/optimising 10BASE-T1L applications. For example, they can be used for:

This page does not aim to give the customer a full guide as to how to uses these available features. Rather this page aims to give the user the specific information they need about the configuration of SPEBlox Long, that will allow them to access the onboard PHY and write their own application.


The DP83TD510E’s internal registers are accessed via an SMI bus. There are three devices on the internal SMI bus on SPEBlox Long, listed below with their addresses.

DP83TD510E: Address = 0x0000

DP83822: Address = 0x0005

STM32L011F4U6: Inactive (no address)

Option 1: Solder to the MDIO and MDC pads on the board

Soldering to these pads gives you full access to the SMI bus that connects to the two onboard PHY chips. These test pads are shown in the image below.

Screenshot 2022-07-14 at 21.28.19.png

Soldering to these test pads give unadulterated access to the onboard SMI bus, and hence requires an external device (such a microcontroller) to generate the SMI signals.

From this point, the PHYs can be accessed directly.

Option 2: Use the STM32 onboard as an SMI parser

The onboard STM32 microcontroller can be configured to run an SMI driver. This has the benefit of not requiring an external SMI device, however it does require the use of SMI driver to be written for the STM32. The onboard STM32 does not perform any SMI configuration on this board (all configuration is completed at startup), hence there is no example code that can be used with this board. BotBlox do have an SMI driver that can be used for this purpose.