1-	« Sudo raspi-config »
Raspberry Pi Software Configuration Tool (raspi-config)
Menu 5 interfacing Options
Configure overclocking for you Pi
Sous Menu    P6 Serial
Enable/Disable shell and kernel messages on the serial connection
Would you like a login shell to be accessible over serial? Non
Would you like the serial port hardware to be enabled?  Oui
The serial login shell is disabled
The serial interface is enabled
2-	Fichier Config .txt
enable_uart=1  ==> ok
dtoverlay=pi3-disable_bt  ==>ok
NOBS Auto-generated Settings:
hdmi_force_hotplug=1
enable_uart=1
dtoverlay=w1-gpio
dtoverlay=pi3-disable_bt
core_freq=250
3- « For older version of Raspbian » (à priori non concerné avec le PI Version 3)
Fichier Cmdline.txt
La Ligne de mon  fichier
dwc_otg.lpm_ensudo raspi-configable=0 console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait splash plymouth.ignore-serial-consoles
4-	Test Picocom
pi@raspberrypi:/ $ picocom -b 1200 -d 7 -p e -f n /dev/ttyAMA0
picocom v1.7
port is        : /dev/ttyAMA0
flowcontrol    : none
baudrate is    : 1200
parity is      : even
databits are   : 7
escape is      : C-a
local echo is  : no
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : sz -vv
receive_cmd is : rz -vv
imap is        :
omap is        :
emap is        : crcrlf,delbs,
Terminal ready
Et puis rien………..