driver: PCNT
1. add PCNT module in periph_ctrl.c/.h
2. add description of PCNT status in pcnt_struct.h
3. add PCNT driver code
4. add PCNT example code.
See merge request !229
1. remove "\n" when calling ESP_LOGX APIs.
2. modify uart_event_t for uart rx data.
3. use MICRO for uart inverse value
4. add uart_tx_data_t for internal tx function.
1. Set XXX_TAG static, remove extern XXX_TAG in uart.h/ledc.h/gpio.h
2. I removed uart_set/get_print_port() functions, these functions are not well tested, I removed them for now.
3. Modify some function names for uart_read/write_bytes
4. Modify uart_write_bytes and uart_write_bytes_with_break.
1. fix bug in ringbuffer.c:
When return an dummy item, free_ptr might exceed rd_ptr, so the write_ptr would overwrite rd_ptr in this case.
2. Delete UART tx task in buffer mode. UART ISR will copy the data from tx buffer to fifo.
1. Add a ring buffer for UART TX.
If the buffer size is set to zero, driver will not use a buffer. But we need a task to send data from buffer to fifo. I tried directly copy data in ISR, but the code looked too long for ISR.
2. Modify the format in uart.h
1. Use esp_log API for LEDC and GPIO code.
2. Modify some API return value.
3. Add ledc_set_pin() for LEDC
4. Modify typo in uart.h
Questions: In uart driver ISR handler, I used xxxFromISR , like xSemaphoreGiveFromISR, do those FromISR functions need to be put in IRAM?
1. configure LEDC timer saparately
2. add peripher_crtl.c/.h
To enable the peripheral modules, we have to set/clear the control register in dport_reg.h.
These bits are disabled by default and they are all in a same register, so we need to add a lock on that.
3. add include esp_err.h in gpio.h
