UART hardware flow control

[awasaw]

Describe the problem you have/What new integration you would like Some devices require flow control when communicating via UART. In this case, it will be useful to add the ability to configure flow control in the UART component. ESP8266 has a hardware implementation of flow control(RTS, CTS, DTR, DSR), which is enabled through the UARTCONF register. This improvement will make it possible to use MAX485 for communication under the RS485 protocol.

Please describe your use case for this integration and alternatives you've tried: I am integrating the electricity meter through the TTL2RS485 converter based on the MAX485 chip, and I need to control the direction of information transfer. At first I wanted to implement a software switch, but delving deeper into the topic, I realized that it was enough to use the hardware capabilities of the board.

Additional context ESP8266_NONOS_SDK/.../uart.h

typedef enum {
    USART_HardwareFlowControl_None    = 0x0,
    USART_HardwareFlowControl_RTS     = 0x1,
    USART_HardwareFlowControl_CTS     = 0x2,
    USART_HardwareFlowControl_CTS_RTS = 0x3
} UART_HwFlowCtrl;

future-request: RS485 serial support / tx enable pin control that can be resolved by this.

[gio-dot]

Ok for the request, but you can use MAX13487 instead (automatic flow control) or an adapter similar to (all with automatic flow control feature) : https://www.amazon.it/DSD-TECH-SH-U12-MAX13487-Raspberry/dp/B07B667STP/ref=sr_1_1?__mk_it_IT=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=max13487&qid=1612797862&sr=8-1 or: https://www.amazon.it/Serial-Mutual-Conversion-Automatic-Control/dp/B07RKY1G71/ref=sr_1_2?__mk_it_IT=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=max13487&qid=1612797948&sr=8-2 or https://it.aliexpress.com/item/32864362561.html?spm=a2g0o.productlist.0.0.5503714fI17cfY&algo_pvid=0046253e-bee0-4b79-b8c4-71c4a32c57fd&algo_expid=0046253e-bee0-4b79-b8c4-71c4a32c57fd-9&btsid=0bb0623f16119252544065155e4078&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

[awasaw]

Ok for the request, but you can use MAX13487 instead (automatic flow control) or an adapter similar to (all with automatic flow control feature) :

In the case of the MAX485, it is possible to change the converter, but the next project will be a control system for the Chinese diesel air-heater "Hcalory" (clone Eberspächer), which uses UART on one wire(not 1-Wire). And I have a choice to use together NPN and PNP transistors to switch rx/tx as it was done in the original board, automatically switching them with RTS signal, or write a software implementation of UART over one wire. In any case, the ability to configure hardware flow control will be useful in the future.

[michelebergo]

Ok for the request, but you can use MAX13487 instead (automatic flow control) or an adapter similar to (all with automatic flow control feature) : https://www.amazon.it/DSD-TECH-SH-U12-MAX13487-Raspberry/dp/B07B667STP/ref=sr_1_1?__mk_it_IT=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=max13487&qid=1612797862&sr=8-1 or: https://www.amazon.it/Serial-Mutual-Conversion-Automatic-Control/dp/B07RKY1G71/ref=sr_1_2?__mk_it_IT=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=max13487&qid=1612797948&sr=8-2 or https://it.aliexpress.com/item/32864362561.html?spm=a2g0o.productlist.0.0.5503714fI17cfY&algo_pvid=0046253e-bee0-4b79-b8c4-71c4a32c57fd&algo_expid=0046253e-bee0-4b79-b8c4-71c4a32c57fd-9&btsid=0bb0623f16119252544065155e4078&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

not always it is possible to use MAX13487 with the automatic flow control so please make the hardware flow control possible please

[michelebergo]

Describe the problem you have/What new integration you would like Some devices require flow control when communicating via UART. In this case, it will be useful to add the ability to configure flow control in the UART component. ESP8266 has a hardware implementation of flow control(RTS, CTS, DTR, DSR), which is enabled through the UARTCONF register. This improvement will make it possible to use MAX485 for communication under the RS485 protocol.

Please describe your use case for this integration and alternatives you've tried: I am integrating the electricity meter through the TTL2RS485 converter based on the MAX485 chip, and I need to control the direction of information transfer. At first I wanted to implement a software switch, but delving deeper into the topic, I realized that it was enough to use the hardware capabilities of the board.

Additional context ESP8266_NONOS_SDK/.../uart.h

typedef enum {
    USART_HardwareFlowControl_None    = 0x0,
    USART_HardwareFlowControl_RTS     = 0x1,
    USART_HardwareFlowControl_CTS     = 0x2,
    USART_HardwareFlowControl_CTS_RTS = 0x3
} UART_HwFlowCtrl;

future-request: RS485 serial support / tx enable pin control that can be resolved by this.

Hi awasaw, can you helping me on implementing the hardware flow control as you did please?

[shawly]

I looked around and found that the ESP-IDF framework supports it so I extended the uart component to enable hardware flow control for ESP32 boards. It's not yet fully complete since I still need to improve validation a little (that's why I didn't create a PR) but it's fully usable, I tested it successfully.

https://github.com/shawly/esphome-components

Technically the framework would also support DSR and DTS but I didn't implement it since I can't test it.

[ssieb]

I don't see why a possible external component is a reason to close a valid feature request.