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M37905F8CSP 参数 Datasheet PDF下载

M37905F8CSP图片预览
型号: M37905F8CSP
PDF下载: 下载PDF文件 查看货源
内容描述: 16位微机的CMOS [16-BIT CMOS MICROCOMPUTER]
分类和应用: 微控制器和处理器外围集成电路光电二极管计算机时钟
文件页数/大小: 35 页 / 489 K
品牌: RENESAS [ RENESAS TECHNOLOGY CORP ]
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MITSUBISHI MICROCOMPUTERS  
M37905F8CFP, M37905F8CSP  
16-BIT CMOS MICROCOMPUTER  
Function overview (CPU reprogramming mode)  
The CPU reprogramming mode is available in the single-chip mode,  
memory expansion mode, and boot mode to reprogram the user  
ROM area only.  
chart, and be sure to follow this flowchart. As shown in Note 1 of Fig-  
ure 8, before selecting the CPU reprogramming mode, set 0to the  
processor mode register 1s bit 7 (the internal ROM bus cycle select  
bit) and set flag I to 1to avoid an interrupt request input.  
When a watchdog timer interrupt request is generated in the CPU  
reprogramming mode, when an input to the RESET pin is L, or  
when the software reset is performed, the flash memory control cir-  
cuit and flash memory control register will be reset.  
In the CPU reprogramming mode, the CPU erases, programs, and  
reads the internal flash memory by writing software commands. Note  
that the user-original reprogramming control software must be trans-  
ferred to the internal RAM in advance to be executed.  
The CPU reprogramming mode becomes active when 1is written  
into the flash memory control registers bit 1 (the CPU reprogram-  
ming mode select bit) shown in Figure 7, and software commands  
become acceptable.  
When the flash memory is reset during the erase or programming  
operation, this operation is cancelled and the target blocks data will  
be invalid. Just before writing a software command related to the  
erase/programming operation, be sure to write to the watchdog  
timer. In the CPU reprogramming mode, be sure not to use the STP  
and WIT instructions.  
In the CPU reprogramming mode, software commands and data are  
all written to and read from even addresses (Note that address A0 in  
byte addresses = 0.) 16 bits at a time. Therefore, a software com-  
mand consisting of 8 bits must be written to an even address; there-  
fore, any command written to an odd address will be invalid. Since  
the write data at the 2nd cycle of a programming command consists  
of 16 bits, this data must be written to even and odd addresses.  
The seaquencer in the flash memory controls the erase and pro-  
gramming operations. What the status of the seaquencer operation  
is and whether the programming or erase operation has been com-  
pleted normally or terminated by an error can be examined by read-  
ing the flash memory control register.  
Figure 7 shows the bit configuration of the flash memory control reg-  
ister.  
Bit 0 (the RY/BY status bit) is a read-only bit for indicating the sea-  
quencer operation. This bit goes to 0(BUSY) while the automatic  
programming/erase operation is active and goes to 1(READY) dur-  
ing the other operations.  
Bit 1 serves as the CPU reprogramming mode select bit. Writing of  
1to this bit selects the CPU reprogramming mode, and software  
commands will be acceptable. Because the CPU cannot directly ac-  
cess the internal flash memory in the CPU reprogramming mode,  
writing to this bit 1 must be performed by the user-original repro-  
gramming control software which has been transferred to the inter-  
nal RAM in advance. To set bit 1 to 1, it is necessary to write 0and  
1to this bit 1 successively. On the other hand, to clear this bit to 0,  
it is sufficient only to write 0.  
Bit 3 (the flash memory reset bit) resets the control circuit of the in-  
ternal flash memory and is used when the CPU reprogramming  
mode is terminated or when an abnormal access to the flash  
memory happens. Writing of 1to bit 3 with the CPU reprogramming  
mode select bit = 1preforms the reset operation. To remove the  
reset, write 0to bit 3 after confirming bit 0 (the RY/BY status bit) be-  
comes 1.  
Bit 5 serves as the user ROM area select bit and is valid only in the  
boot mode. Setting this bit to 1in the boot mode switches an acces-  
sible area from the boot ROM area to the user ROM area. To use the  
CPU reprogramming mode in the boot mode, set this bit to 1. Note  
that when the microcomputer is booted up in the user ROM area,  
only the user ROM area is accessible and bit 5 is invalid; on the other  
hand, when the microcomputer is in the boot mode, bit 5 is valid in-  
dependent of the CPU reprogramming mode. To rewrite bit 5, ex-  
ecute the user-original reprogramming control software transferred  
to the internal RAM in advance.  
Figure 8 shows the CPU reprogramming mode set/termination flow-  
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