Based on HiFlying HF-LPX70 SDK.

The main purpose is to bypass BL602 chip in HiFlying Elfin EG41B device. This makes Air780e direct access via UART1 to main EG41B RS232/RS485 out port.

1. Clone this repo:

git clone https://github.com/freshev/BL602-UART-bridge

2. Install MSYS2

3. Add MSYS2 \usr\bin to PATH environment variable like C:\msys64\usr\bin

4. Run one of the following makeXXX.bat

make_9600_7E1.bat
make_9600_8N1.bat
make_115200_7E1.bat
make_115200_8N1.bat

I.e. make_9600_7E1.bat makes a binary firmware for UART 0 to 1 bridge with baudrate 9600, 7-Even-1, etc.

Burn with SimpleFlasher:

1. Execute BLDevCube\BLDevCube.exe

• Select Partition table to .\chips\bl602\partition\partition_cfg_HF_2M_V2.0.01.toml
• Select Boot2 Bin to .\chips\bl602\bootloader_HF_2M_V3.0.12.bin
• Select Firmware Bin to ..\out\lpt570_full_9600_8N1.bin

2. Connect Elfin EG41B to PC via USB/RS232/RS485 converter. Wires from USB/RS232/RS485 converter to EG41B board MUST be short (not more then 5cm). Otherwise, you will get errors/unstables when reading/writing flash.

3. Connect GPIO8 via a 5-10kOhm resistor to 3.3V (copper pads on the back of the EG41B board).

4. Turn power (off and) on to EG41B board.

5. Start burn, pressing Create and Download button.

6. Break GPIO8 connection to 3.3v.

7. Turn power off and on.

To test bridge:

1. Connect to Air780e (USB-C jack at EG41B board)
2. Open terminal on appeared new third (or second) COM port.
3. in Air780e micropython mode use following script:

from machine import UART
import time
u = UART(1, 9600)
while(True):
if u.any() > 0:
 	r = u.read()
        if r is not None and len(r) > 0:
        print(r.decode(), end = '')
 	    u.write(r)
    time.sleep_ms(10)

4. Symbols from BL602 UART0 (main EG41B input) should be printed in micropython and returned back to UART0.

• The new designed BLEDebug application can show debug output from BLE602 chip (Debug over Bluetooth). See BLEDebug folder.
• Default lib LPBX7Kernel was rewritten to redirect chip debug log to Bluetooth. Also changes made in some project .mk files.
• To make sure the firmware is working - compile and burn the firmware with hfdbg_set_level(1) at src/app_main.c. In this case you should see [UART] (with garbage) message at EG41B main port (PC USB/RS232/RS485 converter configured with 115200, 8N1).
• To completely disable debug log compile and burn the firmware with hfdbg_set_level(0) at src/app_main.c
• BL602 GPIO21 connected to Air780 power.
• BL602 GPIO12 connected to Air780 reset.
• BL602 GPIO16 connected to internal EG41B UART/RS485 converter (DE/!RE pin).

• FreeRTOS Kernel V10.2.1 Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
• HiFlying HF-LPX70 SDK Copyright (C) 2017 ShangHai High-flying Electronics Technology Co.,Ltd.

• BLEDebug screenshot