MCU recommendation

[sanka1p]

Hi All,

I use AVR 0/1 series MCU quite a lot and the best part for me is the Event system in those MCUs. Recently, I need an MCU which runs at higher frequency like 40Mhz+ and have the feature of Event system. I am not keeping my search only till AVR devices. I need advice from folks on other MCUs which has same feature as of Event system. I know that other manufacturers can call these feature with a different name.

what is an Event system?

"The Event System (EVSYS) enables direct peripheral-to-peripheral signaling. It allows a change in one peripheral
(the event generator) to trigger actions in other peripherals (the event users) through event channels, without
using the CPU. It is designed to provide short and predictable response times between peripherals, allowing for
autonomous peripheral control and interaction, and also for synchronized timing of actions in several peripheral
modules. It is thus a powerful tool for reducing the complexity, size, and execution time of the software"


Thank you. v

[ataradov]

SAM D/L/C devices all have event system, which appeared before AVR one. They are based on Cortex-M0+ running at 48 MHz. Sounds exactly like what you want.

[sanka1p]

 That’s awesome and good to know. Just wondering any other MCU series have similar feature ?

[pcprogrammer]

STM32 devices also have some event driven options, but I'm not familiar with what is in AVR series of MCU's and if it really compares to what is in STM32 devices.

[PartialDischarge]

In PsoC you can wire modules, timers, counters, ADCs... so I guess that is your "event" system.

[djacobow]

For those unfamiliar, the "event system" is the ability for on-chip peripherals generate "events" that other peripherals can receive to tell them to do things. The key benefit of this feature is that you can get certain complex behaviors running without the processor being involved at all. For example, you can have a timer generate an event, which triggers and ADC conversion, which on completion generates an event that does a DMA directly to the UART or whatever.

I think many controller families allow you to get this sort of orchestration running. For example, in the PSoC family you can literally wire up peripherals this way in their schematic editor.

[coppice]

For those unfamiliar, the "event system" is the ability to chip peripherals generate "events" that other peripherals can receive to tell them to do things. The key benefit of this feature is that you can get certain complex behaviors running without the processor being involved at all. For example, you can have a timer generate an event, which triggers and ADC conversion, which on completion generates an event that does a DMA directly to the UART or whatever.

I think many controller families allow you to get this sort of orchestration running. For example, in the PSoC family you can literally wire up peripherals this way in their schematic editor.

Most MCUs with a timer and an ADC offer the functionality you describe. Its hard to do regular sampling without it. Event systems try to generalise that, rather than rely on specific pathways around the peripherals, which only account for the use cases the designers thought of.

[eutectique]

Have a look at Nordic Semiconductor nRF52 series.

[SiliconWizard]

This is called "trigger" for some MCUs. Many STM32s do have something like that. And others. In particular, this is how you trigger ADC conversions from a timer, but there are many other possibilities.

[nctnico]

This is called "trigger" for some MCUs. Many STM32s do have something like that. And others. In particular, this is how you trigger ADC conversions from a timer, but there are many other possibilities.

I get the feeling that the AVR system is more like a chunk of programmable logic than some simple signals to start an AD conversion or trigger a DMA. Perhaps the PSOC mentioned by Tom66 comes the closest.

[Siwastaja]

Nearly every MCU has such functionality, the difference is just whether it's completely generic (allowing any peripheral to control any other, in a predictable and easy to program way), or ad hoc mess where the designers just added connections between those peripherals where their customers most usually need them. STM32 belongs in the latter class. And sure enough, usually these "most wanted" connections do the job: for example, timer can trigger ADC, analog comparator can stop PWM cycle, timers can be chained, etc.

In the end, even if you have a completely generic event system, you still have to carefully read through the manuals (or worse, do actual tests) to figure out if the combination of peripherals can do what you need them to do, before even starting the HW design work. So for peripherals A and B to work together, you need to carefully read the specs of both A and B, meaning the ST's messy non-generic way is not actually any worse, just inelegant.

One of the worst features in ST's microcontrollers is very limited and arbitrary DMA mapping which needs careful planning before committing to PCB layout. This has been fixed in some newer generation devices (see DMAMUX).

[PartialDischarge]

In PsoC its important to check the design before doing the actual PCB routing as not all pin routings are available. It has all the devices listed, after that a "Resource Meter" will tell you how much capacity has been used for interconnects etc.

What I like the most is that there some analog glue and the configuration of the peripherals is via windows, attached a couple of examples.