STM CircleOS forum / maximum USART buffer for STM32

marco77 · 2010-04-26 16:42:48

hi

Someone ask me a question about the STM32 but I not sure for the answer.

What is the maximum USART data buffer size that we can use on the STM32?

In the memory map, register for the UART1 are located at:
0x4001 3800 --- 0x4001 3BFF
resulting in 1024 bytes (3FF in hexa).

The STM32 use 24 bytes (0x18) offset registers for configuring the USART
resulting in 1024 - 24 = 1000 bytes not used or reserved I guest.

All this memory configuration is not related to the maximum data buffer
allowed by the USART to transmit.

For the DMA buffer, in the reference manuel, the programmable number of
data to be transferred can go up to 65536.

So, the maximum data buffer for the USART should 65536 bytes.
Does it make sense?

Thank in advance

JM

ntrf.zns · 2010-04-26 19:20:14

0x4001 3800 - 0x4001 3BFF is a memory range for UART pirephiral. It contains a few registers specific to UART and all other space within this range is inaccessable (you can't read or write this part of memory).
There is a single byte buffer available. You can use DMA to link that byte to any memory range in RAM. This allows you to have up to 64KB buffer as part of RAM.

marco77 · 2010-04-27 06:54:09

Thank for your answer.
It is more clearer to me now.

JM

# 1 2010-04-26 16:42:48 maximum USART buffer for STM32

maximum USART buffer for STM32

# 2 2010-04-26 19:20:14 maximum USART buffer for STM32

Re: maximum USART buffer for STM32

# 3 2010-04-27 06:54:09 maximum USART buffer for STM32

Re: maximum USART buffer for STM32

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