MCIMX286CVM4B Freescale Semiconductor, MCIMX286CVM4B Datasheet - Page 1089

• Manufacturer Part Number: MCIMX286CVM4B
• Description: IC MPU I.MX286 289MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: i.MX28r

Specifications of MCIMX286CVM4B

• Core Processor: ARM9
• Core Size: 32-Bit
• Speed: 454MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, MMC, SmartCard, SPI, SSI, UART/USART, USB OTG
• Peripherals: DMA, I²S, LCD, POR, PWM, WDT
• Program Memory Size: 128KB (32K x 32)
• Program Memory Type: Mask ROM
• Ram Size: 32K x 32
• Voltage - Supply (vcc/vdd): 1.25 V ~ 5.25 V
• Data Converters: A/D 17x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 289-LFBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Lead Free Status / Rohs Status: Compliant

14.5.8 Configuring and Programming for Priority Round-Robin
The priority round-robin arbitration scheme requires the use of the following programmable
parameters:
Since these parameters work together, there are trade-offs for the settings.
Note: All of the arbitration parameters must be programmed prior to setting the start
parameter to ‘b1. Any subsequent changes to the arbitration parameters may result in
unpredictable system operation.
14.5.8.1 Definition of the Statistics Window and the Number of Counters
The statistics window sets the length of time used to measure port bandwidth and the number
of counters determines the granularity of the measurement. The values set for both factors
affect bandwidth measurement accuracy, gate area and arbitration latency. Accuracy can
be added to the bandwidth measurements by increasing the number of counters and the
length of time for a calculation. However, this results in a large increase in the gate area.
Arbitration latency for a port is affected by how often bandwidth is updated. This is based
on the amount of time over which each counter tabulates activity: the statistics window
divided by the number of counters. As a general guideline, the statistics window should be
just large enough that the bandwidth used for one complete transaction does not exceed the
allocated bandwidth.
In the EMI, the statistics window is defined as 100 cycles, and there are ten counters per
port.
14.5.8.2 Command Priority, Port Bandwidth, and Bandwidth Overflow
Command priority, bandwidth and bandwidth overflow play an important role in arbitration.
Priority is the most important factor since commands are first sorted into priority groups
based on their priority settings. In a multi-port system, all ports with tight latency
requirements should be assigned higher priority values (lower numbers). Note that the
priority of the command affects both arbitration and placement into the core logic command
queue. As a result, it is more complicated to meet the latency requirements of all ports. For
Freescale Semiconductor, Inc.
• axiY_r_priority, axiY_w_priority, axiY_bdw, axiY_current_bdw, axiY_bdw_ovflow
• arb_cmd_q_threshold
Arbitration
i.MX28 Applications Processor Reference Manual, Rev. 1, 2010
Chapter 14 External Memory Interface (EMI)
1089