Maximum UART Baud Rate

Jan Kijonka
Posts: 28
Joined: Fri Jun 09, 2017 10:17 pm

Maximum UART Baud Rate

Postby Jan Kijonka » Tue Jun 20, 2017 10:45 pm

Hello,

I'm using host MCU with baud rate fine adjust for communication with the ESP8266 ESP-12 module. However, I can't reach any higher baud rate then 350 877 baud (with 1,6 % error). Any higher frequency will cause possible correctly data transmittion (Tx), but missing symbols in receiving data (Rx).

It's far away from the maximum baud rate 40*115200 (4 608 000 baud) declared. I also did not find anyone would use a higher baud rate. Why it doesn't work ? I commonly use the baud rates higher then 1 Mega baud without problems.

Is there any solution to accelerate the communication speed ? Maybe SDIO instead of UART ? What is the hardware connection for SDIO communication, are there any software issues ?

Thank you,

Jan Kijonka

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pratik
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Re: Maximum UART Baud Rate

Postby pratik » Mon Jul 24, 2017 6:28 pm

I have had no problems at 1,152,000! What do you mean that RX is being missed? You mean ESP is not receiving or that your host is not receiving?

You can use HSPI slave for data rate up to 10 mbits/sec average.
HSPI master on ESP8266 works at 12-15 mbits/s
If you use QIO mode, you can get over 20 mbps on HSPI easily.

SDIO is complex, and much more tough to get working. Because ESP needs to boot from HSPI flash then. Modules like ESP12 will not work with SDIO mode. They use SPI flash.
Regards,
Pratik Panda
Website: http://www.PratikPanda.com

Custom firmware, Knowledge base and freelancing (ESP8266/ESP32):
http://www.iot-bits.com

Jan Kijonka
Posts: 28
Joined: Fri Jun 09, 2017 10:17 pm

Re: Maximum UART Baud Rate

Postby Jan Kijonka » Thu Jul 27, 2017 9:30 pm

Thank you,

The problem was in receiving data software in the host MCU (not in ESP), because I have received data byte after byte. It began to omit some received characters at a certain speed. Now I define the expected number of bytes to be received beforehand and the speed is not limited.

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