ST72521 STMICROELECTRONICS [STMicroelectronics], ST72521 Datasheet - Page 207

• Manufacturer Part Number: ST72521
• Description: 8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, FIVE TIMERS, SPI, SCI, I2C, CAN INTERFACE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

To enable programming of all flash sectors, the
device must leave USER mode and be configured
in ICC mode. Once in ICC mode, the ICC protocol
enables an ST7 microcontroller to communicate
with an external controller (such as a PC). ICC
mode is entered by applying 39 pulses on the IC-
CDATA signal during reset. To enter ICC mode,
the device goes through other modes, some
modes are critical because the I/Os PG[7:0] and
PH[7:0] are forced to output push-pull.
Impact on the Application
The PG and PH I/O ports are forced to output
push-pull during three pulses on ICCDATA. In cer-
tain circumstances, this behaviour can lead to a
short-circuit between the I/O signals and V
or an output signal of another application compo-
nent.
In addition, switching these I/Os to output mode
can cause the application to leave reset state, dis-
turbing the ICC communication and preventing the
user from programming the flash.
DD
, V
SS
15.2.9 CAN Cell Limitations
x=limitation present
1
2
WKPS bit.
3
modified.
4
Transmission workaround.
Limitation
Omitted SOF bit
CPU write access
(more than one cycle)
corrupts CAN frame
Unexpected Mes-
sage transmission
Bus Off State Not En-
tered
WKPS Functionality
For details see
Software workaround possible using modified
No software workaround possible. WKPS bit not
Functionality modified for Unexpected Message
1
Section 10.8.5 on page 144
Rev “R” & “Q”
ST72F521
(Flash)
x
x
x
x
2
4
ST72F521 “S”
ST72521 “W”
(Flash) &
ST72521
(ROM)
x
x
x
x
207/211
3