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70592C 数据表(PDF) 64 Page - Microchip Technology |
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70592C 数据表(HTML) 64 Page - Microchip Technology |
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64 / 314 page ![]() PIC24HJXXXGPX06A/X08A/X10A DS70592C-page 64 © 2011 Microchip Technology Inc. 5.2 RTSP Operation The PIC24HJXXXGPX06A/X08A/X10A Flash program memory array is organized into rows of 64 instructions or 192 bytes. RTSP allows the user to erase a page of memory, which consists of eight rows (512 instructions) at a time, and to program one row or one word at a time. Table 24-12 displays typical erase and program- ming times. The 8-row erase pages and single row write rows are edge-aligned, from the beginning of pro- gram memory, on boundaries of 1536 bytes and 192 bytes, respectively. The program memory implements holding buffers that can contain 64 instructions of programming data. Prior to the actual programming operation, the write data must be loaded into the buffers in sequential order. 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 set- ting the control bits in the NVMCON register. A total of 64 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 programming each row. 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 24-19) 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 24-12). EQUATION 5-1: PROGRAMMING TIME 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 The maximum row write time is equal to Equation 5-3. EQUATION 5-3: MAXIMUM ROW WRITE TIME Setting the WR bit (NVMCON<15>) starts the operation, and the WR bit is automatically cleared when the operation is finished. 5.4 Control Registers The two SFRs that are used to read and write the program Flash memory are: • NVMCON • NVMKEY The NVMCON register (Register 5-1) controls which blocks are to be erased, which memory type is to be programmed and the start of the programming cycle. NVMKEY is a write-only register that is used for write protection. To start a programming or erase sequence, the user must consecutively write 0x55 and 0xAA to the NVMKEY register. Refer to Section 5.3 “Programming Operations” for further details. T 7.37 MHz FRC Accuracy ()% FRC Tuning ()% × × ---------------------------------------------------------------------------------------------------------------------------- TRW 11064 Cycles 7.37 MHz 10.05 + () 1 0.00375 – () × × ------------------------------------------------------------------------------------------------ 1.435ms = = TRW 11064 Cycles 7.37 MHz 10.05 – () 1 0.00375 – () × × ------------------------------------------------------------------------------------------------ 1.586ms = = |
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