M37735EHL Datasheet, PDF (6/34 Pages) Mitsubishi Electric Semiconductor – PROM VERSION OF M37735MHLXXXHP

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MITSUBISHI MICROCOMPUTERS
M37735EHLXXXHP
PROM VERSION OF M37735MHLXXXHP
BASIC FUNCTION BLOCKS
The M37735EHLXXXHP has the same functions as the
M37735MHBXXXFP except for the following :
(1) The built-in ROM is PROM.
(2) The status of bit 3 of the oscillation circuit control register 1 (address
6F16) at a reset is different.
(3) The usage condition of bit 3 of the oscillation circuit control register
1 is different.
(4) Part of the processor mode selection method is different.
Accordingly, refer to the basic function blocks description in the
M37735MHBXXXFP except for Figure 1 (bit configuration of
oscillation circuit control register 1), Figure 3 (microcomputer
internal status during reset), and Table 1 (microprocessor mode
selection method).
In the M37735EHLXXXHP, bit 3 of the oscillation circuit control
register 1 must be “0”. (Refer to Figure 1.) Bit 3 is “1” at a reset.
Accordingly, write “0” to bit 3 in the single-chip mode after reset.
Figure 2 shows how to write data in oscillation circuit control register 1.
In the M37735EHLXXXHP, the microprosessor mode cannot be
selected by connecting the CNVSS pin to VCC. Connect the CNVSS
pin to VSS and start the microcomputer operating from the single-
chip mode.
Table 1. Relationship between CNVSS pin input level and processor
modes
CNVSS
Mode
Description
VSS qSingle-chip
Single-chip mode upon starting
qMemory expansion after reset. Each mode can be
qMicroprocessor selected by changing the processor
mode bits by software.
76543210
Address
0 0 CC2 CC1 CC0 Oscillation circuit control register 1 6F16
Main clock division selection bit
0 : Main clock is divided by 2.
1 : Main clock is not divided by 2.
Note. Write to the oscillation circuit control
register 1 as the flow shown in Figure 2.
Main clock external input selection bit
0 : Main-clock oscillation circuit is operating by itself.
Watchdog timer is used at returning from STP state.
1 : Main-clock is input externally.
Watchdog timer is not used at returning from STP state.
Sub clock external input selection bit
0 : Sub-clock oscillation circuit is operating by itself.
Port P76 functions as XCOUT pin.
Watchdog timer is used at returning from STP state.
1 : Sub-clock is input externally.
Port P76 functions as I/O port.
Watchdog timer is not used at returning from STP state.
0 : Always “0” (This bit is “1” at reset, so that write “0” to this bit .)
0 : Always “0” (However, writing data “5516” shown in Figure 2 is possible.)
Clock prescaler reset bit
Fig. 1 Bit configuration of oscillation circuit control register 1 (corresponding to Figure 63 in data sheet “M37735MHBXXXFP”)
Writing data “8016” (LDM instruction)
Reset clock prescaler
Writing data “5516” (LDM instruction)
Writing data “0Y16” (LDM instruction)
CC2 to CC0 selection bits
Next instruction
• How to reset clock prescaler
• How to write in CC2 to CC0 selection bits
Note. “Y” is the sum of bits to be set. For example, when
setting bits 2 and 1 to “1”, “Y” becomes “6”.
Fig. 2 How to write data in oscillation circuit control register 1 (identical with Figure 64 in data sheet “M37735MHBXXXFP”)
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