PIC18F2423-I/ML Microchip Technology, PIC18F2423-I/ML Datasheet - Page 20

• Manufacturer Part Number: PIC18F2423-I/ML
• Description: 16KB, Flash, 768bytes-RAM, 25I/O, 8-bit Family,nanoWatt 28 QFN 6x6mm TUBE
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2423-I/ML

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 25
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT28QFN4 - SOCKET TRANS ICE 28QFN W/CABLEAC164322 - MODULE SOCKET MPLAB PM3 28/44QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PIC18F2423/2523/4423/4523
4.0
4.1
Code memory is accessed one byte at a time via the
4-bit command, ‘1001’ (table read, post-increment).
The contents of memory pointed to by the Table Pointer
(TBLPTRU:TBLPTRH:TBLPTRL) are serially output on
PGD.
TABLE 4-1:
FIGURE 4-1:
DS39759A-page 20
Step 1: Set Table Pointer.
Step 2: Read memory and then shift out on PGD, LSb to MSb.
PGC
Command
PGD
0000
0000
0000
0000
0000
0000
1001
4-Bit
READING THE DEVICE
Read Code Memory, ID Locations
and Configuration Bits
1
1
0E <Addr[21:16]>
6E F8
0E <Addr[15:8]>
6E F7
0E <Addr[7:0]>
6E F6
00 00
2
READ CODE MEMORY SEQUENCE
0
3
0
Data Payload
TABLE READ POST-INCREMENT INSTRUCTION TIMING (1001)
4
1
P5
PGD = Input
1
2
3
MOVLW Addr[21:16]
MOVWF TBLPTRU
MOVLW <Addr[15:8]>
MOVWF TBLPTRH
MOVLW <Addr[7:0]>
MOVWF TBLPTRL
TBLRD *+
4
5
6
7
8
P6
The 4-bit command is shifted in LSb first. The read is
executed during the next 8 clocks, then shifted out on
PGD during the last 8 clocks, LSb to MSb. A delay of
P6 must be introduced after the falling edge of the 8th
PGC of the operand to allow PGD to transition from an
input to an output. During this time, PGC must be held
low (see Figure 4-1). This operation also increments
the Table Pointer by one, pointing to the next byte in
code memory for the next read.
This technique will work to read any memory in the
000000h to 3FFFFFh address space, so it also applies
to the reading of the ID and Configuration registers.
9
LSb
P14
10
1
Core Instruction
11
2
PGD = Output
12
Shift Data Out
3
13
4
14
5
15
© 2005 Microchip Technology Inc.
6
16
MSb
P5A
Fetch Next 4-Bit Command
1
PGD = Input
n
2
n
3
n
4
n