Where do microcontroller designers get peripheral designs from?

[e100]

For example the ESP32 has an onboard CAN controller which is similar in functionality to the NXP SJ1000 CAN controller, but isn't described  in the documentation as being a replica of the SJ1000.

Do chip manufacturers such as NXP license their module designs to other chip designers, or are there specialist design companies that do nothing but design peripheral modules that are licensed to chip manufacturers for use in their own products? I suppose it would be like the ARM model of development, except for peripherals instead of cores.

[SiliconWizard]

Both, but your second option is by far the most common, except for very niche/custom peripherals that are designed in-house.
One leader (similar to ARM as you said) of such IPs is Synopsys. There are many others out there though.

[hans]

Synopsys is indeed a pretty large supplier.

Many USB HS peripheral designs are the same dwc IP design. There are some incremental versions out there, but many communities deliver the same driver stack. You can sometimes take a quick glance at the RTL to see if that matches up.
I think other common peripherals for this treatment is CAN or Ethernet. All those protocols need to comply to standards.
Maybe 16550 UART for some MCUs, but since UART also has taken many forms (SPI as secondary function, for example), I don't think its that common anymore.

On the other hand, things like timers, ADCs, SPIs etc. are much more integral to a clever MCU architecture. If you look at Atmel, Nordic, TI or SiLabs, they have gone to great efforts to support some kind of event system, clock demands, bus designs to support async clocks or power/clock gated etc.

[brucehoult]

Both, but your second option is by far the most common, except for very niche/custom peripherals that are designed in-house.
One leader (similar to ARM as you said) of such IPs is Synopsys. There are many others out there though.

I was going to say "EDA tool suppliers such as Cadence and Synopsys also offer standard IP modules for most common peripherals, DRAM etc"

I don't know which of the two has the larger selection. As I recall, SiFive worked with and offered their customers IP from both of them.

[ataradov]

For CAN specifically, a lot of MCUs use M_CAN IP by Bosch.

And in the RP2040 you can see the name of IPs and their source right in the datasheet.