Freescale Semiconductor 56F8300 Series, Руководство пользователя

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Operating Mode
Technical Summary, Rev. 1
Freescale Semiconductor 2-7
Preliminary
.
2.4 Clock Source
The 56F8357EVM uses an 8.00MHz crystal, Y1, connected to its External Crystal Inputs,
EXTAL and XTAL. To achieve its maximum internal operating frequency, the 56F8357 uses its
internal PLL to multiply the input frequency. An external oscillator source can be connected to
the processor by using the oscillator bypass connectors, JG1 and JG2; see
Figure 2-4 . If the input
frequency is above 8MHz, then the EXTAL input should be jumpered to ground by adding a
jumper between JG1 pins 2 and 3. The input frequency would then be injected on JG2’s pin 2. If
the input frequency is below 4MHz, then the input frequency can be injected on JG1’s pin 2.
Figure 2-4. Schematic Diagram of the Clock Interface
2.5 Operating Mode
The 56F8357EVM provides three BOOT MODE selection jumpers, EXTBOOT, EMI_MODE
and CLKMODE, to provide boot-up MODE options.
Table 2-2. RS-232 Serial Connector Description
P2
Pin # Signal Pin # Signal
1 Jumper to 6 & 4 6 Jumper to 1 & 4
2 TXD 7 CTS
3 RXD 8 RTS
4 Jumper to 1 & 6 9 NC
5 GND
56F8357
EXTERNAL
OSCILLATOR
HEADERS
JG1
1
2
3
1
2
EXTAL
XTAL
JG2
8.00MHz