Problem of using GPIO16 as UART RX with ESP32-D2WD.

thienluan
Posts: 5
Joined: Mon Jan 08, 2018 3:42 am

Problem of using GPIO16 as UART RX with ESP32-D2WD.

Postby thienluan » Tue Jun 12, 2018 8:44 am

Dear ESP supporters,

Our company is making a product using ESP32.

At the first stage, we used the ESP32-WROOM for the demo version. We used the GPIO16 as a UART RX for reading data from the dust sensor PMS7003. And the demo worked very well.

At the second stage, we used the ESP32-D2WD for the real product. However, with the real product, the GPIO16 couldn’t read data for the dust sensor. We found the problem that the GPIO16 swings between 3.3Volt to 1.7Volt.

Is there any difference using the GPIO16 as UART RX between the two parts (ESP32-WROOM vs ESP32-D2WD)? If so, is there any solution to use the GPIO16 as UART RX with ESP32-D2DW?

Thank you very much!

ESP_Sprite
Posts: 1923
Joined: Thu Nov 26, 2015 4:08 am

Re: Problem of using GPIO16 as UART RX with ESP32-D2WD.

Postby ESP_Sprite » Thu Jun 14, 2018 2:01 am

Embedded flash is connected internally to pins GPIO16, GPIO17, SD_CMD, SD_CLK, SD_DATA_0 and SD_DATA_1. So ensure none of these pins are connected externally. (Ref: ESP32 datasheet Section 2.2 Pin Descriptions, Note at bottom). SD_DATA_2 & SD_DATA_3 (GPIOs 9 & 10) are not used for internal flash on ESP32-D2WD and can be used as GPIOs if required.

WiFive
Posts: 1976
Joined: Tue Dec 01, 2015 7:35 am

Re: Problem of using GPIO16 as UART RX with ESP32-D2WD.

Postby WiFive » Thu Jun 14, 2018 3:05 am

ESP_Sprite wrote:SD_DATA_2 & SD_DATA_3 (GPIOs 9 & 10) are not used for internal flash on ESP32-D2WD and can be used as GPIOs if required.

1.8V gpios as a part of vdd_sdio domain. So hopefully gpio 16 was not swinging to 3.3v as d2wd should be strapped to 1.8v.

P.s. esp32 datasheet encoding messed up again

thienluan
Posts: 5
Joined: Mon Jan 08, 2018 3:42 am

Re: Problem of using GPIO16 as UART RX with ESP32-D2WD.

Postby thienluan » Thu Jun 14, 2018 4:17 am

Thank you for your helps!

We will select another pin instead of using GPIO16.

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