README.md Warn about ESP8266 and ESP32 issue.

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--- a/README.md
+++ b/README.md
@@ -4,6 +4,11 @@ This repo provides a driver to receive from IR (infra red) remote controls and
 a driver for IR "blaster" apps. The device drivers are nonblocking. They do not
 require `uasyncio` but are compatible with it.
 
 a driver for IR "blaster" apps. The device drivers are nonblocking. They do not
 require `uasyncio` but are compatible with it.
 

+NOTE: The receiver is intended to be cross-platform. In testing it has proved
+problematic on ESP8266 and ESP32 with a tendency to crash and reboot,
+especially when repeated pulse trains re received. The cause is under
+investigation.
+

 # 1. IR communication
 
 IR communication uses a carrier frequency to pulse the IR source. Modulation
 # 1. IR communication
 
 IR communication uses a carrier frequency to pulse the IR source. Modulation


@@ -27,10 +32,11 @@ Pyboard.
 
 A remote using the NEC protocol is [this one](https://www.adafruit.com/products/389).
 
 
 A remote using the NEC protocol is [this one](https://www.adafruit.com/products/389).
 

-Remotes normally transmit an address and a data byte. The address denotes the
-physical device being controlled. The data is associated with the button on the
-remote. Provision exists for differentiating between a button repeatedly
-pressed and one which is held down; the mechanism is protocol dependent.
+Remotes transmit an address and a data byte, plus in some cases an extra value.
+The address denotes the physical device being controlled. The data defines the
+button on the remote. Provision usually exists for differentiating between a
+button repeatedly pressed and one which is held down; the mechanism is protocol
+dependent.

 
 # 2. Hardware Requirements
 
 
 # 2. Hardware Requirements
 


@@ -40,14 +46,14 @@ For 38KHz devices a receiver chip such as the Vishay TSOP4838 or the
 [adafruit one](https://www.adafruit.com/products/157) is required. This
 demodulates the 38KHz IR pulses and passes the demodulated pulse train to the
 microcontroller. The tested chip returns a 0 level on carrier detect, but the
 [adafruit one](https://www.adafruit.com/products/157) is required. This
 demodulates the 38KHz IR pulses and passes the demodulated pulse train to the
 microcontroller. The tested chip returns a 0 level on carrier detect, but the

-driver design should ensure operation regardless of sense.
+driver design ensures operation regardless of sense.

 
 In my testing a 38KHz demodulator worked with 36KHz and 40KHz remotes, but this
 is obviously not guaranteed or optimal.
 
 
 In my testing a 38KHz demodulator worked with 36KHz and 40KHz remotes, but this
 is obviously not guaranteed or optimal.
 

-The pin used to connect the decoder chip to the target is arbitrary but the
-test programs assume pin X3 on the Pyboard, pin 13 on the ESP8266 and pin 23 on
-ESP32.
+The pin used to connect the decoder chip to the target is arbitrary. The test
+program assumes pin X3 on the Pyboard, pin 23 on ESP32 and pin 13 on ESP8266.
+On the WeMos D1 Mini the equivalent pin is D7.

 
 The transmitter requires a Pyboard 1.x (not Lite) or a Pyboard D. Output is via
 an IR LED which will normally need a transistor to provide sufficient current.
 
 The transmitter requires a Pyboard 1.x (not Lite) or a Pyboard D. Output is via
 an IR LED which will normally need a transistor to provide sufficient current.


@@ -146,7 +152,7 @@ running the chip at 160MHz.
 In general applications should provide user feedback of correct reception.
 Users tend to press the key again if the expected action is absent.
 
 In general applications should provide user feedback of correct reception.
 Users tend to press the key again if the expected action is absent.
 

-Data values passed to the callback are normally positive. Negative values
+Data values passed to the callback are zero or positive. Negative values

 indicate a repeat code or an error.
 
 `REPEAT` A repeat code was received.
 indicate a repeat code or an error.
 
 `REPEAT` A repeat code was received.