Reset Configuration Register (Rcon) - Freescale Semiconductor MCF52277 Reference Manual

Chip Configuration Module (CCM)
Field
15–9 Reserved, must be cleared.
8 FlexBus/SDRAM data pin configuration. Reflects the chosen data bus configuration as determined by
DRAMSEL BOOTMOD[1:0], FB_A21, or SBF_RCON29 as shown below:
BOOTMOD[1:0]
Note: If DRAMSEL is cleared, only 8-bit and 16-bit port sizes are allowed.
0 D[31:16] = SDRAM DDR data[31:16]
D[15:0] = FlexBus data[31:16]
1 D[31:0] = SDRAM SDR data[31:0] or FlexBus data[31:0]
7–6 Chip select configuration. Reflects the chosen chip select configuration.
CSC 00 FB_A[23:22] = FB_A[23:22]
01 FB_A[23:22] = FB_CS5, A22
10 FB_A[23:22] = FB_CS[5:4]
11 Reserved
5 Limp mode bit.
LIMP 0 Normal operation; PLL drives internal clocks.
1 Limp mode; low-power clock divider drives internal clocks.
4 Pad driver load bit. Reflects the chosen pad driver strength for those pins with drive strength control and the
LOAD chosen pad slew rate for those pins with slew rate control.
0 Low drive strength, low slew rate
1 High drive strength, high slew rate
3–2 Boot port size field. Indicates the selection for the boot port size.
BOOTPS 00 32 bits
01 8 bits
10 16 bits
11 16 bits
Note: 32-bit port size cannot be selected when the DRAMSEL is 0.
1 Oscillator clock mode bit.
OSCMODE 0 Crystal oscillator mode
1 Oscillator bypass mode
0 Reserved, must be set.
9.3.2

Reset Configuration Register (RCON)

At reset, the RCON register determines the default operation of certain chip functions. All default
functions defined by the RCON values can be overridden only during reset configuration (see
Section 9.4.1, "Reset Configuration") if the external BOOTMOD[1:0] pins are driven to 10 or 11. RCON
is a read-only register and contains the same fields as the CCR register, except for DRAMSEL.
9-4
Table 9-4. CCR Field Descriptions
DRAMSEL
00 1
01 0
10 FB_A21
11 SBF_RCON29
MCF52277 Reference Manual, Rev. 1
Description
Unified SDR bus/FlexBus
Split DDR bus/FlexBus
Override defaults via data bus (FB_A[21:16]).
Override defaults via serial boot.
Freescale Semiconductor