R8CSLASH20 datasheet(421/501 Pages) RENESAS

421 / 501 page

R8C/20 Group, R8C/21 Group

19. Flash Memory

Rev.2.00 Aug 27, 2008

Page 405 of 458

REJ09B0250-0200

19.7

Notes on Flash Memory

19.7.1

CPU Rewrite Mode

19.7.1.1

Operating Speed

Before entering CPU rewrite mode (EW0 mode), select 5 MHz or below for the CPU clock using the CM06 bit

in the CM0 register and the CM16 to CM17 bits in the CM1 register. This usage note is not needed for EW1

mode.

19.7.1.2

Prohibited Instructions

The following instructions cannot be used in EW0 mode because the flash memory internal data is referenced:

UND, INTO, and BRK instructions.

19.7.1.3

Interrupts

Table 19.9 lists the EW0 Mode Interrupts and Table 19.10 lists the EW1 Mode Interrupts.

NOTES:

1. Do not use the address match interrupt while the command is executed because the vector of the

address match interrupt is allocated on ROM.

2. Do not use the non-maskable interrupt while block 0 is automatically erased because the fixed

vector is allocated block 0.

Table 19.9

EW0 Mode Interrupts

Mode

Status

When Maskable Interrupt

Request is

Acknowledged

When Watchdog Timer, Oscillation Stop

Detection and Voltage Monitor 2 Interrupt

Request are Acknowledged

EW0 During automatic erasing Any interrupt can be used

by allocating a vector to

RAM

Once an interrupt request is acknowledged,

the auto-programming or auto-erasing is

forcibly stopped immediately and resets the

flash memory. An interrupt process starts

after the fixed period and the flash memory

restarts. Since the block during the auto-

erasing or the address during the auto-

programming is forcibly stopped, the

normal value may not be read. Execute the

auto-erasing again and ensure the auto-

erasing is completed normally.

Since the watchdog timer does not stop

during the command operation, the

interrupt request may be generated. Reset

the watchdog timer regularly.

Automatic writing

R8C/20 Datasheet(PDF) 421 Page - Renesas Technology Corp

R8C/20 Datasheet(HTML) 421 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL