PIC18F8621-E/PT Microchip Technology, PIC18F8621-E/PT Datasheet - Page 77

• Manufacturer Part Number: PIC18F8621-E/PT
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,TQFP,80PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F8621-E/PT

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 3.75K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 16x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 80-TFQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT80PT3 - SOCKET TRAN ICE 80MQFP/TQFPAC164320 - MODULE SKT MPLAB PM3 80TQFPAC174011 - MODULE SKT PROMATEII 80TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.2.3
Figure 6-3 shows an example of 16-bit Byte Select
mode for PIC18F8525/8621 devices. This mode allows
table write operations to word-wide external memories
with byte selection capability. This generally includes
both word-wide Flash and SRAM devices.
During a TBLWT cycle, the TABLAT data is presented
on the upper and lower byte of the AD15:AD0 bus. The
WRH signal is strobed for each write cycle; the WRL
pin is not used. The BA0 or UB/LB signals are used to
select the byte to be written based on the Least
Significant bit of the TBLPTR register.
FIGURE 6-3:
 2005 Microchip Technology Inc.
Note 1: This signal only applies to table writes. See Section 5.1 “Table Reads and Table Writes”.
PIC18F8X2X
2: Demultiplexing is only required when multiple memory devices are accessed.
16-BIT BYTE SELECT MODE
AD<15:8>
A<19:16>
AD<7:0>
WRH
WRL
ALE
BA0
OE
UB
I/O
LB
16-BIT BYTE SELECT MODE EXAMPLE
PIC18F6525/6621/8525/8621
373
373
A<20:1>
A<20:1>
138
Flash and SRAM devices use different control signal
combinations to implement Byte Select mode. JEDEC
standard Flash memories require that a controller I/O
port pin be connected to the memory’s BYTE/WORD
pin to provide the select signal. They also use the BA0
signal from the controller as a byte address. JEDEC
standard static RAM memories, on the other hand, use
the UB or LB signals to select the byte.
(2)
A<x:1>
A<x:1>
CE
UB
A0
CE
BYTE/WORD
LB
OE
SRAM Memory
Flash Memory
Address Bus
Data Bus
Control Lines
WR
JEDEC Word
JEDEC Word
OE WR
(1)
D<15:0>
D<15:0>
DS39612B-page 75
(1)
D<15:0>
D<15:0>