pico uart buffer size

[krismc]

I'm trying to move a upython program from an esp32 to an rpi pico. The uart has to cope with a firehose of data from an external modem. On the esp32 I had to increase the receive buffer size to make this work properly

uart=UART(1,115200,tx=2,rx=3,rxbuf=1024)

but I can't find an easy way to do similar on the pico. Are the uarts on the 2 chips really so different?

[robert-hh]

The rxbuf keyword argument is supported by the pico port since March 2021. Which firmware do you use? Does it simply not work or do you get an error? Which behavior do you see?
There is a problem with the pico port that uart.init() resets rxbuf to 256. So you have to set rxbuf again with each call to uart.init().

Edit:

Are the uarts on the 2 chips really so different?

Yes they are different under the hood. But the MicroPython API is mostly the same.

[krismc]

I'm using a spinoff of 1.17, I like it because it preserves ram during deepsleep. To be honest I haven't tried to increase the pico Rx buffer because everywhere online is saying it's limited to 256 bytes

[robert-hh]

If you print the UART object after creating it, it should show a rxbuf value.

[krismc]

tnx, that works, and interesting about init resetting it to the default. I've blundered into a few pico uart quirks. At the start of my code I get away with

from machine import UART; uart=UART(0)

but after a deepsleep I'm obliged to provide a baud

 uart=UART(0, 115200)

[robert-hh]

There is a habit of lightsleep() and deepsleep() to change the peripheral clock. Then the UART speed has to be specified again. This unexpected habit of lightsleep() and deepsleep() was mentioned in various posts and does not affect only UART. e.g. here: #16801

[krismc]

Impressive how you stay abreast of everything Rob, the devil is always in the detail.

…

On Mon, 24 Mar 2025, 6:52 pm Robert Hammelrath, ***@***.***> wrote: There is a habit of lightsleep() and deepsleep() to change the peripheral clock. Then the UART speed has to be specified again. This unexpected habit of lightsleep() and deepsleep() was mentioned in various posts and does not affect only UART. e.g. here: #16801 <#16801> — Reply to this email directly, view it on GitHub <#16966 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACBCWGNL46TONLINXEOJKAT2V62VJAVCNFSM6AAAAABZMTWGWCVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTENJZHA3DCMY> . You are receiving this because you authored the thread.Message ID: ***@***.*** com>

[robert-hh]

Not me, it is Damien who knows and remembers everything.