Epson S1C33210 manual 165

II CORE BLOCK: BCU (Bus Control Unit)

These bus operations are shown in the figure below, taking the example of the A0 method. With the BSL method, the following adjustments should be made when reading the figure.

(1)For data reads, the operation is as shown in the figure below.

(2)For little-endian data writes, read A0 as #BSC, and #WRH as #BSH.

(3)For big-endian data writes, read A0 as #BSL, and #WRL as #BSH. For information on memory connection, see Figure 4.18.

Little-endian

31			Source (general-purpose register)										0					Bus operation
		Byte 3			Byte 2			Byte 1				Byte 0		No.	A1	A0	#WRH #WRL		15	Data bus		0
15				2		0	15		1				0	1	0	0	0	0		Byte 1	Byte 0
														2	1	0	0	0		Byte 3	Byte 2
		A[1:0]=10						A[1:0]=00
					Destination (16-bit device)
	Big-endian
31			Source (general-purpose register)										0					Bus operation
		Byte 3			Byte 2			Byte 1				Byte 0		No.	A1	A0	#WRH #WRL		15	Data bus		0
15				1		0	15		2				0	1	0	0	0	0		Byte 3	Byte 2
														2	1	0	0	0		Byte 1	Byte 0
		A[1:0]=00						A[1:0]=10
					Destination (16-bit device)
								Figure 4.5			Word Data Writing to a 16-bit Device
	Little-endian
31		Destination (general-purpose register)											0					Bus operation
		Byte 3			Byte 2			Byte 1				Byte 0		No.	A1	A0	#WRH #WRL		15	Data bus		0
15					2	0	15			1			0	1	0	0	1	1		Byte 1	Byte 0
														2	1	0	1	1		Byte 3	Byte 2
		A[1:0]=10						A[1:0]=00
					Source (16-bit device)
	Big-endian
31		Destination (general-purpose register)											0					Bus operation
		Byte 3			Byte 2			Byte 1				Byte 0		No.	A1	A0	#WRH #WRL		15	Data bus		0
15					1	0	15			2			0	1	0	0	1	1		Byte 3	Byte 2
														2	1	0	1	1		Byte 1	Byte 0
		A[1:0]=00						A[1:0]=10
					Source (16-bit device)
								Figure 4.6			Word Data Reading from a 16-bit Device
	Little-endian
31			Source (general-purpose register)										0					Bus operation
		Byte 3			Byte 2			Byte 1				Byte 0		No.	A1	A0	#WRH #WRL		15	Data bus		0
							15		1				0	1	∗	0	0	0		Byte 1	Byte 0
								A[1:0]=∗ 0
							Destination (16-bit device)
	Big-endian
31			Source (general-purpose register)										0					Bus operation
		Byte 3			Byte 2			Byte 1				Byte 0		No.	A1	A0	#WRH #WRL		15	Data bus		0
							15		1				0	1	∗	0	0	0		Byte 1	Byte 0
								A[1:0]=∗ 0
							Destination (16-bit device)

Figure 4.7 Half-word Data Writing to a 16-bit Device

S1C33210 FUNCTION PART EPSON B-II-4-13