Hi
I don't have experience with using blhost but if the serial loader has been installed into flash I would expect that a reset would cause it to start.
I have, however, worked with the SDP protocol that blhost uses and used the following technique:
1. I build the serial loader using the bat file/make file method which generates and output using (see make_uTaskerSerialBoot_GNU_iMX):
# Create SDP output file and show its size
uTaskerSerialSDP.elf: $(OBJS) $(OBJS2_SDP) iMX_RT_10XX_SDP_BOOT.ld
$(CC_LNK) $(C_FLAGS) -Os -g -TiMX_RT_10XX_SDP_BOOT.ld -nostartfiles -Xlinker --gc-sections -lm -Wl,-Map=uTaskerSerialSDP_BM.map -o uTaskerSerialSDP.elf $(OBJS) $(OBJS2_SDP)
$(CC_OBJ) --only-section=.data --only-section=.init --only-section=.text --only-section=.rodata --only-section=.vectors --output-target=binary uTaskerSerialSDP.elf uTaskerSerialSDP.bin
$(CC_SIZE) uTaskerSerialSDP.elf
$(CC) -v
This output is suitable for use by loading with the SDP protocol (it is loaded and run in OCRAM)
I think I set this define in config.h
#define CONFIG_SDP_LOADER // build the serial loader to work as a downloaded loader with the NXP serial download protocol
2. The serial loader can be build with any options and the one I use is SREC via USB-CDC
3. When this binary is installed and started (I think it is equivalent to when you load your flashloader and will be suitable for any boards that can run the serial loader since it will be configured with the same flash driver, and can be modified to add more functions such as test functions for production) it runs this serial loader and so appears as a CDC device. Like this the host can load SREC files (in order to install the final serial loader + application into flash) and can be commanded to start with the "go" command.
Regards
Mark
P.S. I use a second i.MX RT for production programming that uses the SDP protocol via USB (as host) connected to fresh i.MX RTs in their ISP mode. It detects when they enumerate, installs the uTaskerSerialSDP.bin that I generated for the target and starts it. The device then enumerates as USB-CDC and the host sends the SREC interface "bc", "ld", SREC image, "go" commands to install the complete serial loader/application.
At the same time the i.MX RT host controls the bed of nails tester to test the board and program other parts on it.
I have used the technique a number of times in quite large volumes - recently I tested/programmed 1000 boards myself and they all programmed without any glitches.