444
Table 20.7
On-Board Programming Mode Selection
Mode Selections
FV
PP
12 V
*
MD
1
12 V
*
MD
0
0
Notes
Boot mode
Mode 2
0: V
IL
1: V
IH
Mode 3
12 V
*
1
User programming
mode
Mode 2
1
0
Mode 3
1
1
Note:
*
For details on the timing of 12 V application, see notes 6 to 8 in the Notes on Use of Boot
Mode at the end of this section.
In boot mode, the mode control register (MDCR) can be used to monitor the mode (mode 2
or 3) in the same way as in normal mode.
Example: Set the mode pins for mode 2 boot mode (MD
1
= 12 V, MD
0
= 0 V).
If the mode select bits of MDCR are now read, they will indicate mode 2 (MDS1 = 1,
MDS0 = 0).
20.3.1
Boot Mode
To use boot mode, a user program for programming and erasing the flash memory must be
provided in advance on the host machine (which may be a personal computer). Serial
communication interface channel 1 is used in asynchronous mode. If the H8/3337YF is placed in
boot mode, after it comes out of reset, a built-in boot program is activated. This program starts by
measuring the low period of data transmitted from the host and setting the bit rate register (BRR)
accordingly. The H8/3337YF’s built-in serial communication interface (SCI) can then be used to
download the user program from the host machine. The user program is stored in on-chip RAM.
After the program has been stored, execution branches to address H'F7E0 in the on-chip RAM,
and the program stored on RAM is executed to program and erase the flash memory. Figure 20.4
shows the boot-mode execution procedure.
HOST
Receive data to be programmed
Transmit verification data
H8/3337YF
RxD
1
TxD
1
SCI
Figure 20.3 Boot-Mode System Configuration