Digi BL1800 user manual Memory, Sram, Flash Eprom

3.7 Memory

3.7.1 SRAM

The Jackrabbit is designed to accept 32K to 512K of SRAM packaged in an SOIC case.

Standard Jackrabbit models come with 128K of SRAM. A factory-installed option for 512K of SRAM is available. Figure 14 shows the locations and the jumper settings for the jump- ers at JP1 used to set the SRAM size. The “jumpers” are 0 Ω surface-mounted resistors.

U1

GND	J1
	J2
VIN GND

J3

				SRAM
		128K			512K
		JP1			JP1
		3	2	1	3	2	1
					U4
	J4				RS-232			J5
GND	VCC			JP1			VCC	GND
PA0	PA1						RXB	RXC
PA2	PA3			U5			TXB	TXC
PA4	PA5						PC0	PC1
PA6	PA7	U3					PC2	PC3
GND	GND						PC4	PC5
					SRAM
PB0	PB1						PC6	PC7
PB2	PB3						AD0	AGND
PB4	PB5						DA0	DA1
PB6	PB7						PD0	PD1
WDO	PCLK						PD2	PD3
GND	PE7						PD4	PD5
PE6	PE5						PD6	PD7
PE4	PE3						GND	GND
PE2	PE1						485–	485+
PE0	GND				U6		VCC	VCC
HV0	HV1						SM0	SM1
HV2	HV3					IOBEN		STAT
K	+RAW				RS-485		GND	VBAT
GND	VCC	Y3					/RST	GND
								RESET

JACKRABBIT Z-World, Inc.

Figure 14. Jackrabbit Jumper Settings for SRAM Size

NOTE: For ordering or other information involving the factory-installed 512K SRAM option, call your Rabbit sales representative or distributor.

No 0 Ω surface-mounted resistors are installed at JP1 for 32K SRAM.

3.7.2 Flash EPROM

The Jackrabbit is also designed to accept 128K to 512K of flash EPROM packaged in a TSOP case.

NOTE: Rabbit recommends that any customer applications should not be constrained by the sector size of the flash memory since it may be necessary to change the sector size in the future.

A Flash Memory Bank Select jumper configuration option exists at JP3 with 0 Ω surface- mounted resistors for Jackrabbit boards labeled 175-0255. This option, used in conjunc- tion with some configuration macros, allows Dynamic C to compile two different co-resi- dent programs for the upper and lower halves of the 256K flash in such a way that both programs start at logical address 0000. This is useful for applications that require a resi- dent download manager and a separate downloaded program. See Technical Note 218, Implementing a Serial Download Manager for a 256K Flash, for details.

User’s Manual 33