docu: added status

README.md

@@ -5,6 +5,12 @@ Bridge between Wifi and CAN.
 ![image](doc/wifican_hardware_top.jpg)
 ![image](doc/wifican_hardware_bottom.jpg)
 
+## News
+
+### 2023-10-10
+
+Receive path runs much more stable with the own TWAI FIFO driver. Transmit path not yet implemented.
+
 ## Motivation
 
 SavvyCAN is a great open-source CAN tool, and the ESP32RET is assumingly a pretty good interface between the PC and multiple CANs.
@@ -17,28 +23,33 @@ The good old ESP32 board had the following issues:
 - Using a more up-to-date ESP32s3 board reveals incompatibilites:
     - The ESP32s3 does not support classic bluetooth, only BT low energy. This is not compatible with the ELM327 emulation, at least not out-of-the box.
     - The ESP32_CAN driver hangs endless loop in a high-prio CAN driver task, maybe due to changes in the scheduling concept of the espressif twai driver.
+
+Even when switching to the ESP32s3, there are stability issues with the original espressif TWAI driver, see doc/crashlog.md .
 
 Out of this situation, the plan is create a minimal single channel device, which is a bridge between Wifi and CAN, and is still compatible to SavvyCAN.
 
 ## Solution
 
-The better way would be to add fixes to the ESP32RET, but for experimentation the following approach was chosen:
+The better way would be to add fixes to the ESP32RET and the espressif TWAI driver, but for experimentation the following approach was chosen:
 - Instead of using the Libs which ESP32RET uses, copy the content directly into the project folder. This makes it easy to modify and develop, and to keep a consistent state.
 - Single CAN channel: use the built-in TWAI of the ESP. No SPI, no MCP..., no FD support.
 - One hard-coded configuration of the board. No EEPROM parameters.
+- The only configuration option is the selection between Wifi-AP and Wifi-Station. The selection is done by a switch on a digital input.
 - Kicked-out bluetooth completely.
 - Kicked-out serial GVRET completely.
+- Kicked-out the espressif TWAI driver (which has stability issue in the queue handling), and created a simple FIFO based receive path.
 
 So we end-up with the following features for the moment:
 - Single CAN channel. Configured to 500kBaud.
-- Wifi connection to an existing wifi network (configured in the wifi_credentials.h file)
-- Connection between PC and wifican runs over the existing wifi, using GVRET over wifi, which is in fact a telnet TCP connection.
+- Wifi connection to an existing wifi network (configured in the wifi_credentials.h file) or providing an access point.
+- Connection between PC and wifican runs over wifi, using GVRET over wifi, which is in fact a telnet TCP connection.
 - The usb-serial-port is used just for debugging. No serial GVRET support.
 
 ## Quick Start Guide
 
 - Install the Arduino IDE and the ESP32s3 board support.
 - Solder a 3.3V CAN transceiver board to the ESP32s3 board. This needs just four wires: 3.3V, ground, CAN_RX (pin 4), CAN_TX (pin 5).
+- Connect a switch, which connects the pin35 either to ground or to pin 47.
 - Connect the ESP32s3 board at the "COM" USB (not the "USB"-USB) to the PC.
 - Rename the wifi_credentials_template.h to wifi_credentials.h, and enter your wifi credentials there.
 - Build and download the project in the Arduino IDE.
@@ -51,7 +62,7 @@ So we end-up with the following features for the moment:
 
 ## Results of reverse-engineering
 
-### How does a CAN transmission work?
+### How did a CAN transmission work?
 
 - CANManager::sendFrame
 - CAN_COMMON.sendFrame(...)
@@ -60,7 +71,7 @@ So we end-up with the following features for the moment:
 
 The states and transitions of the ESP32S3 CAN driver are described here: https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/api-reference/peripherals/twai.html
 
-### How does the CAN reception work?
+### How did the CAN reception work (in the old world with espressif TWAI driver?
 
 - During startup, the task task_LowLevelRX is started.
 - The task_LowLevelRX suspends in twai_receive().
@@ -79,7 +90,7 @@ The states and transitions of the ESP32S3 CAN driver are described here: https:/
     - CANManager::displayFrame --> wifiGVRET.sendFrameToBuffer(frame, whichBus)
 
 
-### How is the receive callback path configured?
+### How was the receive callback path configured?
 attachCANInterrupt() --> CAN_COMMON::setGeneralCallback() sets the cbGeneral.
 canBuses[i]->watchFor() --> setRXFilter()
 CAN_COMMON::attachCANInterrupt() --> CAN0.setCallback() -->