MCF5270CAB100 Freescale Semiconductor, MCF5270CAB100 Datasheet - Page 106

• Manufacturer Part Number: MCF5270CAB100
• Description: MCU V2 COLDFIRE 64K SRAM 160-QFP
• Manufacturer: Freescale Semiconductor
• Series: MCF527xr

Specifications of MCF5270CAB100

• Core Processor: Coldfire V2
• Core Size: 32-Bit
• Speed: 100MHz
• Connectivity: EBI/EMI, Ethernet, I²C, SPI, UART/USART
• Peripherals: DMA, WDT
• Number Of I /o: 39
• Program Memory Type: ROMless
• Ram Size: 64K x 8
• Voltage - Supply (vcc/vdd): 1.4 V ~ 1.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 160-QFP
• Processor Series: MCF527x
• Core: ColdFire V2
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: NNDK-MOD5272-KIT, NNDK-MOD5270-KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Details

Enhanced Multiply-Accumulate Unit (EMAC)
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
The round-to-nearest-even technique is also known as convergent rounding.
4.4.1.1.2
The presence of rounding logic in the output datapath of the EMAC requires that special care be
taken 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 following 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:
The following code performs the EMAC state restore:
4-10
— If the lsb of R0.U = 0 and R0.L =0x8000, the number is rounded down.
then Result = R0.U
else if R0.L > 0x8000
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
then Result = R0.U + 1
else if lsb of R0.U = 0
MCF5271 Reference Manual, Rev. 2
then Result = R0.U
else Result = R0.U + 1
; 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
/* R0.L = 0x8000 */
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