Specifications

FC protocol description
Developer’s Serial Bootloader, Rev. 13
Freescale Semiconductor 7
Figure 4. StartUp communication with calibration
If the MCU is operating at the correct data rate (no calibration is possible or required, and the MCU clock
is crystal driven), the PC can immediately send an ACK, skipping the calibration phase entirely (Figure 2).
Figure 5. Start-Up communication without calibration
MCU
PC
A
C
K
A
C
K
HOOK-UP TIME-OUT
NO-BREAK TIME-OUT
b
r
e
a
k
b
r
e
a
k
A
C
K
CALIBRATION UNSUCCESSFUL
OR ONLY ROUGH CORRECTION DONE
CALIBRATION SUCCESSFUL
ACK IS SENT AT CORRECT DATARATE
ACK IS SENT AT UNCERTAIN DATA RATE
FROM NOW ON, THE COMMUNICATION IS AT THE CORRECTLY SPECIFIED DATA RATE
ONLY 0XFC CHARACTER CAN BE RECEIVED
NO-BREAK TIME-OUT
z
e
r
o
p
u
l
s
e
z
e
r
o
p
u
l
s
e
NO-ZERO TIME-OUT
NO-ZERO TIME-OUT
MCU
PC
A
C
K
A
C
K
A
C
K
NO CALIBRATION REQUIRED
ACK IS SENT AT CORRECT DATA RATE
ACK IS SENT AT SPECIFIED DATA RATE
CORRECT 0xFC CHARACTER IS RECEIVED WITHIN TIME-OUT
HOOK-UP TIME-OUT
NO-BREAK TIME-OUT