Renesas EDK3687 user manual SPI Eeprom, Crystal Choice, Removable Component Information

4.2.2.CRYSTAL CHOICE

The operating crystal frequency has been chosen to support the fastest operation with the fastest serial operating speeds. The value of the crystal is 18.432MHz.

The following table shows the baud rates and Baud Rate Register (BRR) setting required for each communication rate using the above default operating speed. It also confirms the resultant baud rate and the bit error rate that can be expected.

Baud Rate Register Settings for Serial Communication Rates

SMR		0			1			2			3
Setting:
Comm.	BRR	Actual	ERR	BRR	Actual	ERR	BRR	Actual	ERR	BRR	Actual	ERR
Baud	setting	Rate	(%)	setting	Rate	(%)	setting	Rate	(%)	setting	Rate	(%)
110	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	81	110	-0.22
300
	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	119	300	0.00	29	300	0.00
1200
	Invalid	Invalid	Invalid	119	1200	0.00	29	1200	0.00	7	1125	-6.25
2400
	239	2400	0.00	59	2400	0.00	14	2400	0.00	3	2250	-6.25
4800
	119	4800	0.00	29	4800	0.00	7	4500	-6.25	1	4500	-6.25
9600
	59	9600	0.00	14	9600	0.00	3	9000	-6.25	Invalid	Invalid	Invalid
19200
	29	19200	0.00	7	18000	-6.25	1	18000	-6.25	Invalid	Invalid	Invalid
38400	14	38400	0.00	3	36000	-6.25	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid
57600	9	57600	0.00	2	48000	-16.67	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid
115200	4	115200	0.00	0	144000	25.00	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid
230400*	2	192000	-16.67	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid
460800*	0	576000	25.00	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid	Invalid

TABLE 4-2 CRYSTAL FREQUENCIES FOR RS232 COMMUNICATION

*Note: The device used to convert the RS232 serial information to logic signals for the microcontroller is limited to

120kBaud. The rates above this level can only be utilised if the user provides direct logic level communications.

The user may replace the HC49/U surface mounted AT cut crystal with another of similar type within the operating frequency of the microcontroller device. Please refer to the hardware manual for the microcontroller for the valid operating range.

Alternatively the user may fit an oscillator module – or provide an external clock source. When providing an oscillator module or external source it is highly recommended that the load capacitors for the AT crystal are removed from the PCB. These are physically placed within the PCB outline of the oscillator module for easy location and to ensure they are removed when using this option.

When changing the crystal frequency the pre-loaded debugging monitor will not function. In this situation the user is responsible for providing code to evaluate the device away from the default operating speed.

4.2.3.REMOVABLE COMPONENT INFORMATION.

This information is provided to allow the replacement of components removed from the board as described in section 4.2.2.

Component	Cct. Ref	Value	Rating		Manufacturer
Load Resistor (X2)	R8	1MΩ	0805	1%	Welwyn WCR Series
Load Resistor (X3)	R7	1MΩ	0805	1%	Welwyn WCR Series
Load capacitors (X2)	C2,C3	12pF	0603	10% 25V	AVX 0603 3 A 150 KAT
Load capacitors (X3)	C4,C5	15pF	0603	10% 25V	AVX 0603 3 A 150 KAT

TABLE 4-3: REMOVABLE COMPONENT INFORMATION

Care must be taken not to damage the tracking around these components. Only use soldering equipment designed for surface mount assembly and rework.

4.3. SPI EEPROM

The board has been tested with an Atmel AT25040N-10SA-2.7 SPI EEPROM device (Not supplied).

The device should be connected to P30, P31, P32 and P67 using 0R links on R15, R16, R17 and R21. Alternative connections are available, refer to section 5.3 for more information.

Do not fit the CAN transceiver if the SPI device is fitted while using the settings above.

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