The connectivity line is a specific requirement, not a general one
An MCU with an Ethernet MAC, two CAN controllers, several UARTs and a USB device port is a different animal from a general-purpose M4. The reason to move to one is usually a single missing interface, and the risk is that fixing that one interface breaks the other four that were already working.
The three parts in this group
| Part | Position in the line | Where it usually fits |
|---|---|---|
| AT32F455 | Baseline of the Ethernet-capable group | Industrial gateways, protocol bridges |
| AT32F456 | Middle member with more on-chip memory | Devices with local logging or a web page |
| AT32F457 | Top of the group | Multi-protocol controllers, instrument front panels |
All three share the interface set that makes this tier useful: Ethernet MAC, multiple CAN channels, USB, and enough serial ports to bridge protocols without external glue logic.
What to check before committing
The PHY interface, not the MAC
The MAC being present is the easy half. Confirm whether the reference design uses RMII or MII, and whether the 50 MHz clock is generated by the PHY or by the MCU. That single decision changes which pins are used and whether you need an external oscillator.
CAN channel count and pin assignment
Two CAN controllers on paper frequently means two CAN controllers that share a pin group with something else you need. Map every CAN, UART and Ethernet pin on the package you intend to buy before ordering samples.
Ethernet plus USB at the same time
Running both concurrently puts pressure on the clock tree and on DMA bandwidth. If your application does both, test them simultaneously rather than sequentially — the failure mode only appears under combined load.
Protocol stack porting
A lightweight TCP/IP stack ported to one M4 usually ports to another, but the Ethernet driver layer is vendor-specific. Expect to rewrite the MAC driver and keep the rest.
A realistic migration order
- Pin table for Ethernet, CAN and UART only — ignore everything else at this stage.
- Bench a minimal board that runs Ethernet and one CAN channel at the same time.
- Port the protocol stack and confirm sustained throughput, not just a ping.
- Add the remaining interfaces one at a time, re-testing EMC after each significant change.
Doing it in this order means a pin conflict is discovered in week one instead of after the layout is finished.
Where the cost actually moves
For a connectivity design the saving is rarely in the MCU unit price alone — it shows up in what you no longer need around it. A part that carries the MAC, the CAN controllers and the USB device port removes external transceivers' glue logic and lets you shrink the board. If your current design already has those external parts working and certified, that saving is smaller than it looks.
Ethernet-capable parts we currently hold: AT32F455VET7, AT32F456VET7 and AT32F457VET7. The wider line is on Microcontrollers / MCUs and the interface side of the catalogue is under Interface / RF Chips.
Verify before you commit: pinout, peripheral mapping and electrical limits differ between part numbers and between silicon revisions. Always confirm against the current official datasheet and errata for the exact order code you intend to use.
Questions & Answers
Does the AT32F455 have an Ethernet MAC?
Yes, this group is defined by carrying an on-chip Ethernet MAC along with multiple CAN channels and USB. Confirm the PHY interface type and pin assignment for the exact order code you plan to use.
Can I reuse my existing TCP/IP stack?
The stack layer usually ports across, but the Ethernet MAC driver is vendor-specific and has to be rewritten. Plan for that as a distinct task rather than a configuration change.
Is MII or RMII the better choice?
RMII uses fewer pins and is the usual choice for a new layout. MII may be the faster path if you are adapting an existing board that already routes MII signals.
What is the biggest risk when replacing a connectivity-line MCU?
Pin conflicts between interfaces you need simultaneously. Build the pin table for all of them together, not one interface at a time.
Recommended next steps
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