Datasheet

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SBAS317E − APRIL 2004 − REVISED MAY 2006
www.ti.com
37
Serial Flash Programming Mode
Serial Flash Programming mode (SFPM) is used to
download Program and Data Memory into the onboard
Flash Memory on the MSC120x. It is initiated by holding
the P1.0/PROG
pin low during the reset cycle, as shown
in Figure 23. After the reset cycle, the host can
communicate with the MSC120x through USART0. Refer
to application note SBAA076 (www.ti.com) for serial
programming commands and protocol.
In SFPM, the MSC120x uses the internal oscillator in low
frequency mode (that is, the external clock is disabled).
The internal oscillator frequency is affected by the power
supply voltage and device temperature. Therefore, in
order to avoid losing communication during programming,
it is important to have a stable power supply and
temperature environment during serial communication.
The recommended baud rate range for SFPM is 2400 to
19200. If communication errors occur, decreasing the
baud rate may improve communication performance.
Also note that in SFPM, the Brownout Detect circuit is
disabled and AV
DD
must be > 2.0V.
INTERRUPTS
The MSC120x use a three-priority interrupt system. As
shown in Table 6, each interrupt source has an
independent priority bit, flag, interrupt vector, and enable
(except that nine interrupts share the Auxiliary Interrupt,
AI, at the highest priority). In addition, interrupts can be
globally enabled or disabled. The interrupt structure is
compatible with the original 8051 family. All of the standard
interrupts are available.
MSC120x
P1.0/PROG
P3.0 RXD
P3.1 TXD
Serial
Port 0
RST
DV
DD
Reset Circuit (or V
DD
)
RS232
Transceiver
Host PC
or
Serial Terminal
AV
DD
NOTE: Serial programming is selected when P1.0/PROG is low at reset.
Figure 23. Serial Flash Programming Mode