Instead of having a send buffer as member `esp_wifi` netdev, a local variable is used now as send buffer. This avoids the need for a locking mechanism and reduces the risk of deadlocks.
Receive call back function `_esp_wifi_rx_cb` is called from WiFi hardware driver with a pointer to a frame buffer that is allocated in the WiFi hardware driver. This frame buffer was freed immediately after copying its content to a single local receive buffer of the `esp_wifi` netdev. The local receive buffer remained occupied until the protocol stack had processed it. Further incoming packets were dropped. However, very often a number of subsequent WiFi frames are received at the same time before the first one is processed completely. Having the single local receive buffer to hold only one received frame, led to a number of lost packets, even at low network load. Therefore, a ringbuffer of rx_buf elements was introduced which doesn't store the frames directly but only references to the frame buffers allocated in WiFi hardware driver. Since there is enough memory to hold several frames, the frames buffers allocated in WiFi hardware driver aren't freed immediatly any longer but are kept until the frame is processed by the protocol stack. This results in a much less loss rate of packets.
Events of different type can be pending at the same time. Therefore it is not possible to use ascending identifiers for the presence of a pending event. Rather, each event type has to be represented by one bit. Thes bits ORed identify all types of pending events. In the esp_wifi_isr function all pending events are then handled in one call. Otherwise, some events might be lost.
The Atlas Scientific pH OEM sensor is a small circuit to be embedded in
end products to measure the pH value with any commercially available pH
electrode
- Serial.print() and Serial.println() have been extended to support:
- unsigned int
- long
- unsigned long
- The SerialFormat BIN has been implemented
- Serial.println(void) has been added
UART FIFO must contain only 1 byte when newlib's `printf` function is used. Otherwise, outputs that are still not sent over UART are lost when `printf` is called asynchronousely.
To avoid unresolved symbols for unused functions during linking, compiler option `-ffunction-sections` is used now. Linker option `--warn-unresolved-symbols` is removed to get errors if required symbols cannot be resolved.
The modules `newlib, `newlib_syscalls_default` and `stdio_uart` are now used by default for output to the UART interface. This also reduces the dependency rules.
The overridden stdio functions `puts`, `putchar` and `printf` were removed. Instead, the corresponding newlib functions are always used. Using the newlib functions fixes output conflicts when using `f *` functions like `fprintf`,` fputs`, ... with `stdout` as the file parameter.
This is to avoid conflics with other config.h files, e.g. when building
for esp8266 where $(NEWLIB)/xtensa-lx106-elf/include/config.h gets
included instead.
