PIC24EP256GU810-I Datasheet, PDF (136/622 Pages) Electronic Film Capacitors, Inc. – 16-Bit Microcontrollers and Digital Signal Controllers with High-Speed PWM, USB and Advanced Analog

dsPIC33EPXXX(GP/MC/MU)806/810/814 and PIC24EPXXX(GP/GU)810/814
5.2 RTSP Operation
The dsPIC33EPXXX(GP/MC/MU)806/810/814 and
PIC24EPXXX(GP/GU)810/814 Flash program memory
array is organized into rows of 128 instructions or
384 bytes. RTSP allows the user application to erase a
page of memory, which consists of eight rows
(1024 instructions) at a time, and to program one row
or one word at a time. Table 32-12 lists typical erase and
programming times. The 8-row erase pages and single
row write rows are edge-aligned from the beginning of
program memory, on boundaries of 3072 bytes and
384 bytes, respectively.
The program memory implements holding buffers,
which are located in the write latch area, that can con-
tain 128 instructions of programming data. Prior to the
actual programming operation, the write data must be
loaded into the buffers sequentially. The instruction
words loaded must always be from a group of
64 boundary.
The basic sequence for RTSP programming is to set up
a Table Pointer, then do a series of TBLWT instructions
to load the buffers. Programming is performed by
setting the control bits in the NVMCON register. A total
of 128 TBLWTL and TBLWTH instructions are required
to load the instructions.
All of the table write operations are single-word writes
(two instruction cycles) because only the buffers are
written. A programming cycle is required for program-
ming each row. For more information on erasing and
programming Flash memory, refer to Section 5.
“Flash Programming” (DS70609) in the “dsPIC33E/
PIC24E Family Reference Manual”.
5.3 Programming Operations
A complete programming sequence is necessary for
programming or erasing the internal Flash in RTSP
mode. The processor stalls (waits) until the
programming operation is finished.
The programming time depends on the FRC accuracy
(see Table 32-19) and the value of the FRC Oscillator
Tuning register (see Register 9-4). Use the following
formula to calculate the minimum and maximum values
for the Row Write Time, Page Erase Time and Word
Write Cycle Time parameters (see Table 32-12).
EQUATION 5-1: PROGRAMMING TIME
-7---.-3---7-----_M-----_H----_z----_-----_--_F----_R----_C-----_A----_c--_c---_u---_r--^Ta---_c---_y---_---%------_-----_--_F----_R----_C-----_T---_u---_n---_i--_n---_g----_--%---
For example, if the device is operating at +125°C, the
FRC accuracy will be ±5%. If the TUN<5:0> bits (see
Register 9-4) are set to ‘b111111, the minimum row
write time is equal to Equation 5-2.
EQUATION 5-2: MINIMUM ROW WRITE
TIME
T_RW = _{7---.--3---7-----M}-----_H----_z----_-----_-¹-1--¹---⁰₊---⁶--0-⁴--.-0-^C--5--^y--_-^c--_^l--^e---^s_--1-----_–----0---.--0---0---3---7---5---_-= 1.435ms
The maximum row write time is equal to Equation 5-3.
EQUATION 5-3: MAXIMUM ROW WRITE
TIME
T_RW = _{7---.--3---7-----M}-----_H----_z----_-----_¹--1-¹---⁰-_–--⁶--0-⁴--.--0-^C--5--^y-_--^c--_^l--^e---_^s--1----_–-----0---.-0---0---3---7---5----_ = 1.586ms
Setting the WR bit (NVMCON<15>) starts the
operation and the WR bit is automatically cleared
when the operation is finished.
DS70616G-page 136
 2009-2012 Microchip Technology Inc.