PIC24H Microchip Technology, PIC24H Datasheet - Page 56

• Manufacturer Part Number: PIC24H
• Description: Flash Programming Specification
• Manufacturer: Microchip Technology

dsPIC33F/PIC24H PROGRAMMING SPECIFICATION
5.2.1
The SIX control code allows execution of dsPIC33F/
PIC24H Programming Specification assembly instruc-
tions. When the SIX code is received, the CPU is sus-
pended for 24 clock cycles, as the instruction is then
clocked into the internal buffer. Once the instruction is
shifted in, the state machine allows it to be executed over
the next four clock cycles. While the received instruction
is executed, the state machine simultaneously shifts in
the next 4-bit command (see Figure 5-2).
FIGURE 5-2:
FIGURE 5-3:
DS70152D-page 56
PGC
PGD
Note 1: Coming out of Reset, the first 4-bit control
P2
PGC
PGD
Execute PC – 1,
Fetch SIX Control Code
1
0
2: TBLRDH, TBLRDL, TBLWTH and TBLWTL
Fetch REGOUT Control Code
Execute Previous Instruction,
2
SIX SERIAL INSTRUCTION
EXECUTION
0
P3
code is always forced to SIX and a forced
NOP instruction is executed by the CPU.
Five additional PGC clocks are needed
on start-up, thereby resulting in a 9-bit
SIX command instead of the normal 4-bit
SIX command. After the forced SIX is
clocked in, ICSP operation resumes as
normal (the next 24 clock cycles load the
first instruction word to the CPU).
instructions must be followed by a NOP
instruction.
1
3
0
1
2
4
0
PGD = Input
0
3
0
5
SIX SERIAL EXECUTION
REGOUT SERIAL EXECUTION
Memory Entry
4
0
Only for
Program
6
0
0
P4
7
0
1
0
8
CPU Held in Idle
2
0
9
P4
LSB X
7
1
8
2
P1B
P5
X
P1A
3
PGD = Input
1
X
LSb
Preliminary
P1
4
X
2
1
5
3
X
2
6
24-Bit Instruction Fetch
Shift Out VISI Register<15:0>
X
4
3
7
5.2.2
The REGOUT control code allows for data to be
extracted from the device in ICSP mode. It is used to
clock the contents of the VISI register out of the device
over the PGD pin. After the REGOUT control code is
received, the CPU is held Idle for 8 cycles. After these
eight cycles, an additional 16 cycles are required to clock
the data out (see Figure 5-3).
The REGOUT code is unique because the PGD pin is
an input when the control code is transmitted to the
device. However, after the control code is processed,
the PGD pin becomes an output as the VISI register is
shifted out.
5
X
Note:
4
PGD = Output
8
X
6
...
17
11
X
10
18 19 20 21 22
X
REGOUT SERIAL INSTRUCTION
EXECUTION
Data is transmitted on the falling edge and
latched on the rising edge of PGC. For all
data transmissions, the Least Significant
bit (LSb) is transmitted first.
12
11
X
13
12
X
14
13
X
15 16
14
© 2007 Microchip Technology Inc.
X MSB
MSb
23 24
P4a
No Execution Takes Place,
Fetch Next Control Code
1
P4a
PGD = Input
0
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Execute 24-Bit Instruction,
Fetch Next Control Code
2
1
0
0
3
2
0
0
4
3
0
0
4
0