Motorola ColdFire MCF5281 - Manual (Page 42)

Overview
1-10 Freescale Semiconductor
1.1.8 SDRAM Controller
The SDRAM controller provides all required signals for glueless interfacing to a variety of
JEDEC-compliant SDRAM devices. SRAS/SCAS address multiplexing is software configurable for
different page sizes. To maintain refresh capability without conflicting with concurrent accesses on the
address and data buses, SRAS, SCAS, DRAMW, SDRAM_CS[1:0], and SCKE are dedicated SDRAM
signals.
1.1.9 Test Access Port
The MCF5282 supports circuit board test strategies based on the Test Technology Committee of IEEE and
the Joint Test Action Group (JTAG). The test logic includes a test access port (TAP) consisting of a 16-state
controller, an instruction register, and three test registers (a 1-bit bypass register, a 256-bit boundary-scan
register, and a 32-bit ID register). The boundary scan register links the device’s pins into one shift register.
Test logic, implemented using static logic design, is independent of the device system logic.
The MCF5282 implementation supports the following:
• Perform boundary-scan operations to test circuit board electrical continuity
• Sample MCF5282 system pins during operation and transparently shift out the result in the
boundary scan register
• Bypass the MCF5282 for a given circuit board test by effectively reducing the boundary-scan
register to a single bit
• Disable the output drive to pins during circuit-board testing
• Drive output pins to stable levels
1.1.10 UART Modules
The MCF5282 contains three full-duplex UARTs that function independently. The three UARTs can be
clocked by the system clock, eliminating the need for an external crystal.
Each UART has the following features:
• Each can be clocked by the system clock, eliminating a need for an external UART clock
• Full-duplex asynchronous/synchronous receiver/transmitter channel
• Quadruple-buffered receiver
• Double-buffered transmitter
• Independently programmable receiver and transmitter clock sources
• Programmable data format:
— 5–8 data bits plus parity
— Odd, even, no parity, or force parity
— One, one-and-a-half, or two stop bits
• Each channel programmable to normal (full-duplex), automatic echo, local loop-back, or remote
loop-back mode
• Automatic wake-up mode for multidrop applications
• Four maskable interrupt conditions
• All three UARTs have DMA request capability
• Parity, framing, and overrun error detection
• False-start bit detection
• Line-break detection and generation
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3