import sensor
import image
import lcd
import time
import utime
from machine import UART
from Maix import GPIO
from fpioa_manager import *

fm.register(34,fm.fpioa.UART1_TX)
fm.register(35,fm.fpioa.UART1_RX)
uart_out = UART(UART.UART1, 115200, 8, None, 1, timeout=1000, read_buf_len=4096)

while 1 :
    uart_out.write('hello_world\n')
    utime.sleep_ms(100)

and I tried to adapt it for my application (which is face recognition) like this:

import sensor
import image
import KPU as kpu
import lcd
import time
import utime
from machine import UART
from Maix import GPIO
from fpioa_manager import *
fm.register(34,fm.fpioa.UART1_TX)
fm.register(35,fm.fpioa.UART1_RX)
uart_out = UART(UART.UART1, 115200, 8, None, 1, timeout=1000, read_buf_len=4096)
sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.run(1)
task = kpu.load(0x300000)
anchor = (1.889, 2.5245, 2.9465, 3.94056, 3.99987, 5.3656, 5.155437, 6.14367, 6.3784, 7.26)
a = kpu.init_yolo2(task, 0.5, 0.3, 5, anchor)
while 1 :
        img = sensor.snapshot()
        code = kpu.run_yolo2(task, img)
        if code:
            for i in code:
                 uart_out.write(i)
                 a = img.draw_rectangle(i.rect())
a= kpu.definit(task)

Initially it was a similar code that I used without UART on the MaixpyIDE and connected via USB which worked well.
But when I put it in the boot.py it doesn't write the coordinate to i on the Raspberry.
I would point that I didn't put an SD card in the UnitV-OV7740. Could it be that I don't have enough memory to run this new code?
Thanks a lot !

Thanks a lot.