Chapter 3 4 Kbyte EEPROM Module (S12XEETX4KV2)
MC9S12XDP512 Data Sheet, Rev. 2.11
158 Freescale Semiconductor
Figure 3-14. Determination Procedure for PRDIV8 and EDIV Bits
PRDIV8 = 1
yes
no
PRDIV8 = 0 (reset)
>12.8 MHz?
EECLK = (PRDCLK)/(1+EDIV[5:0])
PRDCLK = oscillator_clock
PRDCLK = oscillator_clock/8
PRDCLK[MHz]*(5+Tbus[µs]) no
EDIV[5:0]=PRDCLK[MHz]*(5+Tbus[µs])–1
yes
START
Tbus < 1µs?
an integer?
EDIV[5:0]=INT(PRDCLK[MHz]*(5+Tbus[µs]))
1/EECLK[MHz] + Tbus[ms] > 5
AND
EECLK > 0.15 MHz
?
END
yes
no
EDIV[5:0] > 4?
ALL COMMANDS IMPOSSIBLE
yes
no
ALL COMMANDS IMPOSSIBLE
no
TRY TO DECREASE Tbus
yes
oscillator_clock