This esptool.py wrapper lets you use RTS/CTS for ESP8266/ESP32
chip resets instead of the usual RTS/DTR. It only works with
FTDI-based USB to serial adapters.
Normally, CTS is an input. On FTDI chips, CTS can be reconfigured as
an output by entering bitbang mode. This wrapper replaces all of the
internal esptool.py serial routines with direct calls into
libftdi1 and libusb-1.0 to dynamically switch between normal and
bitbang modes as needed to make the typical reset-into-bootloader
sequence work.
This was tested on Linux only. Some of the ctypes library loading
probably needs to be tweaked for other OSes.
$ ./esptool-ftdi.py
usage: ./esptool-ftdi.py <path-to-esptool.py> [args...]
Simply prepend esptool-ftdi.py to your existing esptool command
line. For example, instead of:
$ esptool.py chip_id
esptool.py v2.3.1
Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to Espressif device: Timed out waiting for packet header
$
run this and be much happier:
$ ./esptool-ftdi.py esptool.py chip_id
esptool-ftdi.py wrapper
esptool.py v2.3.1
/dev/ttyUSB0 is at bus 3 dev 78 interface 0
Connecting.....
Detecting chip type... ESP32
Chip is ESP32D0WDQ6 (revision (unknown 0xa))
Features: WiFi, BT, Dual Core, VRef calibration in efuse
Uploading stub...
Running stub...
Stub running...
Chip ID: 0xe2b4e62dac76
Hard resetting via RTS pin...
$
In your Makefile, after the line
include $(IDF_PATH)/make/project.mk
add
ESPTOOL_FTDI := /path/to/esptool-ftdi.py
ESPTOOLPY_SERIAL := $(PYTHON) $(ESPTOOL_FTDI) $(ESPTOOLPY_SRC) --chip esp32 --port $(ESPPORT) --baud $(ESPBAUD) --before $(CONFIG_ESPTOOLPY_BEFORE) --after $(CONFIG_ESPTOOLPY_AFTER)
This could be simplified with some changes in ESP-IDF.