can I use all 8 UARTs of STM32F091VC?

[aatif shaikh]

Hi All,

Currently, I'm working on project wherein I need the maximum number of UARTs I can get. After doing some research, I came across the STM32F091VC controller which has the 8 UART (max number of UARTs ST can provide). Unfortunately, there is not a single eval-board/ discovery/ nucleo board which has this controller with all UART's pin out on connectors. Hence, before I proceed with my own hardware design, I wanted to know, whether I can use all the 8 UART without any issue, or I've to use some sort of management to use all of them together.

Any tips regarding board design, information regarding previous issues, or the link of other references would be highly appreciated.

Regards,

Aatif Shaikh

[S.Ma]

Normally you can use all peripherals.

Note that USART vs UART vs LPUART have small differences to check out:

• max baud rate
• HW flow control

If you plan to use any DMA, you might not be able to plumb all UARTs.

Also make sure you have enough RAM for all buffers (protocol dependent?)

If you need more UART in the future by cascading MCUs, keep an SPI pinout available. (USART <=> SPI <=> USART' is implementable (USARTs over SPI)

[aatif shaikh]

thanks for the answer,

1. All the UART will be 8-N-1 mode and HW flow control will be none.
2. I'll not going to use the DMA, and I will use the standard peripheral libraries.
3. I don't feel buffer memory will be any issue as I'll create most probably around 500-bytes buffer for each UART (overall 4KB(UART)+ 2KB(other process))

Thanks for the suggestion on how I can increase the number of UARTs. Moreover, STM32F091VC has the 256K flash and 32KB RAM, is there any better version of ST controller with 8 or higher UART, also has more RAM, runs on high clock rate (72Mhz and above).?

Regards,

Aatif Shaikh

[After Forever · Accepted solution]

> is there any better version of ST controller with 8 or higher UART, also has more RAM, runs on high clock rate (72Mhz and above).?

Yeah, there are 100 and 144 pin STM32F413 models which have 6 UARTS and 4 USARTS, so 10 in total. NUCLEO-F413ZH is available too with such a MCU.

Or, if you need even more firepower, you can use one of many STM32H7 series microcontrollers, e.g. STM32H743ZI, a Nucleo board is avaialbe too, it has 4 UARTS, 4 USARTS, and 1 LPUART, so 9 in total.

[waclawek.jan]

One think to notice on the 'F09x is, that USARTs 3 to 8 share a single interrupt vector.

Not really an issue, just a minor annoyance. Cube/CubeMX users probably won't even notice.

JW

[aatif shaikh]

@Community member​ thanks a lot mate, this is really helpful, sharing single vector will be slightly pain, as I'll not properly able to assign the priorities in a convenient way.

@After Forever​ you're a life savior, I'll probably move to the NUCLEO-F413ZH. Now, all I've to check, is whether they've provided all the necessary pins (RX and TX of the UART) on the morpho connectors or not.

[Uwe Bonnes]

But at least on the F09 there is a register to see what uart interrupt fired

[Piranha]

Also F7 series has 4 USARTs + 4 UARTs = 8 total. You get twice the processing power of F4 with almost the same complexity. In contrast H7 is quite a different and more complex beast.

[waclawek.jan]

You mean SYSCFG_ITLINE29 ?

Yes it's neat. It's a pity ST's documentation does not handle well description of the modules' interconnection.

JW

[aatif shaikh]

NUCLEO-F413ZH seems to be the best option for me. Unfortunately, I'm not able to find any authentic and rightful details of this board.

Even on the STM site:" https://www.st.com/en/evaluation-tools/nucleo-f413zh.html#overview ", the majority of the resource files are of different NUCLEOs (mostly NUCLEO-F207ZG). There is a huge lack of information about this board makes me feel sad. 

So, If the UART's pins aren't going to be available on the MORPHO connectors than that board will be useless for me.

does this board launch in the market recently?. If so, I'll have to make a custom-made board.