Updated README for latest ESP32 library changes. They added writes re…

…maining!

git-svn-id: svn://192.168.1.10/public/Zimodem@18856 0d6f1817-ed0e-0410-87c9-987e46238f29

README

@@ -12,7 +12,7 @@ Building:
 ---------
 To build this firmware for the ESP-01 or ESP-12, I used the Arduino IDE rev1.6.11 (or any version before or equal to 1.8.5) with the Arduino Generic ESP8266 Module installed from the head dev at https://github.com/esp8266/Arduino.  Using that version of the library not the official Boards Manager distribution (via Additional Boards Manager URL http://arduino.esp8266.com/stable/package_esp8266com_index.json) was important to resolving several problems (specifically 300ms/byte socket write times).  How you get there from here was tricky.  I followed the standard instructions for installing an ESP board, found where it dropped the package (on Windows 10, it was in:c:\users\<myname>\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\... I dropped the new stuff from github in there instead of the old stuff, and then went into the new "tools" directory and ran get.py. ** 
 
-To build this firmware for the ESP-32, I also used the Arduino IDE rev 1.6.11 (or any version before or equal to 1.8.5) with the Arduino ESP32 Dev Module installed from the head dev at https://github.com/espressif/arduino-esp32, with the following settings: QIO, 4MB, 80MHZ, 921600, NONE, Avrisp Mk II **.  I found that baud changing corrupts the serial bus as of 1/13/2018, so the following changes were made to the base libraries: 
+To build this firmware for the ESP-32, I also used the Arduino IDE rev 1.6.11 (or any version before or equal to 1.8.5) with the Arduino ESP32 Dev Module installed from the head dev at https://github.com/espressif/arduino-esp32 (~11/01/2019), with the following settings: QIO, 4MB, 80MHZ, 921600, NONE, Avrisp Mk II **.  I found that baud changing corrupts the serial bus as of 1/13/2018, so the following changes were made to the base libraries: 
 > Added to esp32-hal-uart.c:
 void uartChangeBaudRate(uint8_t uart_nr, uint32_t baudrate)
 { 
@@ -32,29 +32,15 @@ void uartChangeConfig(uint8_t uart_nr, uint32_t config)
     }
     UART_MUTEX_UNLOCK();
 }
-size_t uartWritesRemaining(uart_t* uart)
-{
-    if(uart == NULL) {
-        return;
-    }
-    size_t remain;
-    UART_MUTEX_LOCK();
-    remain = 0x7F - uart->dev->status.txfifo_cnt;
-    UART_MUTEX_UNLOCK();
-    return remain;
-}
 > Added to esp32-hal-uart.h:
 void uartChangeBaudRate(uint8_t uart_nr, uint32_t baudrate);
 void uartChangeConfig(uint8_t uart_nr, uint32_t config);
-size_t uartWritesRemaining(uart_t* uart);
 > Added to HardwareSerial.cpp:
 void HardwareSerial::changeBaudRate(int baudRate) { uartChangeBaudRate(_uart_nr, baudRate); }
 void HardwareSerial::changeConfig(uint32_t config) { uartChangeConfig(_uart_nr, config); }
-size_t HardwareSerial::availableForWrite() { return uartWritesRemaining(_uart); }
 > Added to HardwareSerial.h:
 void changeBaudRate(int baudRate);
 void changeConfig(uint32_t config);
-size_t availableForWrite();
 
 ** Both versions of the firmware are built with SPIFFS enabled.  On the ESP8266, I used settings of 1M/160k, but you may want to alter that depending on your hardware and needs.