MCF5282CVF80J Freescale Semiconductor, MCF5282CVF80J Datasheet - Page 89

• Manufacturer Part Number: MCF5282CVF80J
• Description: IC MPU 512K FLASH 256MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: MCF528xr

Specifications of MCF5282CVF80J

• Core Processor: Coldfire V2
• Core Size: 32-Bit
• Speed: 80MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, SPI, UART/USART
• Peripherals: DMA, LVD, POR, PWM, WDT
• Number Of I /o: 150
• Program Memory Size: 512KB (512K x 8)
• Program Memory Type: FLASH
• Ram Size: 64K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 256-MAPBGA
• Processor Series: MCF528x
• Core: ColdFire V2
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: NNDK-MOD5282-KIT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: No

This method minimizes rounding bias and creates as statistically correct an answer as possible.
The rounding algorithm is summarized in the following pseudocode:
if R0.L < 0x8000
else if R0.L > 0x8000
else if lsb of R0.U = 0
else Result = R0.U + 1
The round-to-nearest-even technique is also known as convergent rounding.
3.3.1.2
The presence of rounding logic in the EMAC output datapath requires special care during the EMAC’s
save/restore process. In particular, any result rounding modes must be disabled during the save/restore
process so the exact bit-wise contents of the EMAC registers are accessed. Consider the memory structure
containing the EMAC programming model:
struct
} macState;
The following assembly language routine shows the proper sequence for a correct EMAC state save. This
code assumes all Dn and An registers are available for use, and the memory location of the state save is
defined by A7.
EMAC_state_save:
This code performs the EMAC state restore:
EMAC_state_restore:
Freescale Semiconductor
•
If R0.L is 0x8000, R0 is half-way between two 16-bit numbers. In this case, rounding is based on
the lsb of R0.U, so the result is always even (lsb = 0).
— If the lsb of R0.U equals 1 and R0.L equals 0x8000, the number is rounded up.
— If the lsb of R0.U equals 0 and R0.L equals 0x8000, the number is rounded down.
then Result = R0.U
then Result = R0.U + 1
then Result = R0.U
macState {
int acc0;
int acc1;
int acc2;
int acc3;
int accext01;
int accext02;
int mask;
int macsr;
move.l
clr.l
move.l
move.l
move.l
move.l
move.l
move.l
move.l
move.l
movem.l #0x00ff,(a7)
Saving and Restoring the EMAC Programming Model
macsr,d7
d0
d0,macsr
acc0,d0
acc1,d1
acc2,d2
acc3,d3
accext01,d4
accext23,d5
mask,d6
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3
/* R0.L = 0x8000 */
; save the macsr
; zero the register to ...
; disable rounding in the macsr
; save the accumulators
; save the accumulator extensions
; save the address mask
; move the state to memory
Enhanced Multiply-Accumulate Unit (EMAC)
3-11