megaAVR 0-series

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Product Change Notification - RMES-27EGDU414 - 22 Nov 2019 - CCB 3634 Final Notice: Qualification of MMT as an additional assembly site for selected Atmel products available in 32L VQFN (5x5x0.9mm) package.

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Estimated First Ship Date:
December 22, 2019 (Date Code: 1952)

 

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Revision History:
January 03, 2019: Issued initial notification.
November 22, 2019: Issued final notification. Attached the Qualification Report. Revised the affected parts list. Provided estimated first ship date to be on December 22, 2019.

 

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MMT - Microchip Thailand

 

"Dare to be naïve." - Buckminster Fuller

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The 48-pin QFN pads will be taller by probably the middle of next year ('20)

Product Change Notification - RMES-19QWFS608 - 26 Nov 2019 - Memo # ML112019001A Initial Notice: Introduction of new package for existing ATMEGA3209 and ATMEGA4809 device families available in 48L UQFN (6x6x0.5mm) package.

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Affected CPNs:

 

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Pre Change:
Available in 48L UQFN (6x6x0.5mm)  

Post Change:
Available in 48L VQFN (6x6x0.9mm)  

 

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Reason for Change:
To improve manufacturability by qualifying new package for existing device families affected.

 

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Estimated Qualification Completion Date:
April 2020

 

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"Dare to be naïve." - Buckminster Fuller

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I have questions, LOTS of them. Hope that answers will be generally useful to others. I recognize that there MAY be (and probably are) answers to some of these questions in the documentation, but I've not been able to sort them out, so far.

 

1) What is PORTMUX? Is it "just" a cross-point switch or does it alter the functionality of the pins (input vs output, pullup/down, etc)? That is, does the peripheral take over the full function of the pin, as in M328P? Does more have to be done for pin control with PORTMUX compared to AVR-standard?

 

2) EVSYS? Can someone describe the broad behavior of this thing? I see a block diagram with gates and flipflops but that does not give me any sense of what it really does.

 

3) I'm struggling to understand differences between TCA and TCB peripherals. Can anyone help with a high-level overview?

 

4) CRC - it appears that the hardware CRC module only works on data being written to flash as part of programming. In other words, it appears to NOT be available for generation of serial message CRCs. Is this correct?

 

5) AVR-standard generally have an interlock between the SPI and the SS pin; to do certain things, the SS pin has to be configured a certain way. It is not at all clear whether there are similar requirements for the USART in SPI mode. Any help, here?

 

Thanks

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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ka7ehk wrote:

2) EVSYS? Can someone describe the broad behavior of this thing? I see a block diagram with gates and flipflops but that does not give me any sense of what it really does.

 

3) I'm struggling to understand differences between TCA and TCB peripherals. Can anyone help with a high-level overview?

 

4) CRC - it appears that the hardware CRC module only works on data being written to flash as part of programming. In other words, it appears to NOT be available for generation of serial message CRCs. Is this correct?

 

5) AVR-standard generally have an interlock between the SPI and the SS pin; to do certain things, the SS pin has to be configured a certain way. It is not at all clear whether there are similar requirements for the USART in SPI mode. Any help, here?

 

The Event System (EVSYS) basically allows one peripheral to control another. On devices with DMA you can do stuff like have the DMA copy data from a USART when a byte received event is generated, replacing the usual interrupt handler. Since these don't have DMA the system is a bit more limited. You can clock counters from other peripherals, say a pin change event on a GPIO or the custom logic.

 

TCA has waveform generation (advanced PWM) capability, TCB has the ability to timestamp inputs which lets you measure periods or determine frequency. The latter can be quite handy for stuff like MODBUS where the end of a frame is a gap, which you can use TCB to measure. Actually you can use the pin change event to do that with TCA too I think, I haven't looked at it.

 

CRC does seem to have been nerfed a bit compared to the XMEGA, you kinda wonder why they bother having it just for flash and not adding a CPU interface that would have been incredibly useful.

 

USART in SPI mode is master only, so there is no SS pin. The main advantage is that it's buffered, where as the SPI peripherals are not.

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ka7ehk wrote:
1) What is PORTMUX? Is it "just" a cross-point switch or does it alter the functionality of the pins (input vs output, pullup/down, etc)?

That's a good question. I think when you enable event output in the PORTMUX, it does take control of the pins. But when you use it to multiplex peripherals to different ports, I think this depends on the peripheral, not PORTMUX itself. Frankly, this requires testing.

 

ka7ehk wrote:
2) EVSYS? Can someone describe the broad behavior of this thing? I see a block diagram with gates and flipflops but that does not give me any sense of what it really does.

On each peripheral chapter, you will find an "events" section. This will explain whether this peripheral can generate or use events. For example, for TCB it says:

 

The TCB is an event generator. (...)

The peripheral accepts one event input. (...)

This means TCB both generates and accepts events. The event generator routes these events between peripherals. Basically, it allows some simple actions, that would normally be executed by an ISR, to happen fully in hardware.

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Thanks,

 

There is some useful help here!

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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mojo-chan wrote:
... you kinda wonder why they bother having it just for flash ...
Flash is one transistor per bit whereas SRAM is four or six transistors per bit; SRAM is more tolerant of ionizing radiation and high temperature.

Some MCU for geo-physical have a boot ROM and SRAM; fire the internal battery, bootload, then down the bore hole.

MRAM has some radiation tolerance though its temperature range is for most automotive applications and some avionics.

mojo-chan wrote:
... and not adding a CPU interface that would have been incredibly useful.
There might be an arbitration impact versus CRC connected to I/O (UART, USART, etc as CRC is common for communication protocols)

ADC has an accumulator; somewhat similar complexity could be additional for that CRC interface.

 


RIP Opportunity | The Embedded Muse 368

HT-DAB-1 Reference Design Kit - VORAGO | Mouser

Aerospace | Everspin (MRAM)

 

"Dare to be naïve." - Buckminster Fuller

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This is my thinking on the event system:

On the 328p you might write an interrupt handler, triggered by an "input" peripheral, to change the state of an "output" peripheral.  The event system lets you shortcut the function of the interrupt handler.  And in some cases I believe the behavior is asynchronous.

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What is PORTMUX? Is it "just" a cross-point switch or does it alter the functionality of the pins (input vs output, pullup/down, etc)? That is, does the peripheral take over the full function of the pin, as in M328P? Does more have to be done for pin control with PORTMUX compared to AVR-standard?

In general, the peripherals on the Mega-0 seem to be less "take over" than they were in previous Mega parts.  For instance, in UART initialization, you need to set the TX pin as an output, and maybe set it to ONE as well (the datasheet doesn't say you need to set it to ONE, but it's in the example.)

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Thanks on that. I thought that I had seem some posts that suggested that (about PORTMUX), hence the question.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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