SM2965 ISP technology features and applications

Single chip microcomputer STM32L151CCU6

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1 Introduction

The emergence of in-system programming (ISP) technology is a breakthrough in traditional programming methods. It refers to the technology of reprogramming devices in a user-designed microcontroller system to configure new system functions. The program code (firmware) is online. ) Download to the program memory. Following SST's introduction of the ISP-enabled FlashFlex51 [1] series of microcontrollers, PHILISPS, WINBOND, LG, ATMEL, SynCMOS and other companies have introduced 51 series of microcontrollers with ISP/IAP (In-ApplICation Programming) functions [2] ]. The performance enhancement of these devices is also manifested in: (1) The internal ROM uses Flash memory, the capacity reaches 32-64k bytes, the internal RAM capacity reaches 512-1024 bytes; (2) the special function register is added, and the control function is further enhanced; 3) Internal configuration watchdog timer reset circuit; (4) ALE output can be disabled to reduce EMI; (5) Dual DPTR pointer, etc. These functions further simplify the external expansion of the microcontroller, forming a true "single piece" structure. In the POS charging terminal, the SynCMOS SM2965 was replaced as the main processor, and the ISP function can be easily realized by modifying the hardware using the serial port of the microcontroller. This article mainly analyzes the ISP features of SM2965 and the precautions in use.

2 Features of SM2965

Compared with the standard 80C52, the SM2965 has the following features: 1 programming voltage 5V; 264k bytes of on-chip flash memory, divided into 128 pages, 512 bytes per page (including download program space for implementing ISP functions); 3 implementation of ISP The function download program space size can be set to N × 200H (N = 0 ~ 8); 4256 bytes of on-chip RAM + 768 bytes of on-chip extended RAM (ERAM); 5 watchdog timer; 6 pairs of PLCC and QFP package model has added P4 port: P4.0~P4.3; 7 is to reduce EMI, ALE signal output can be disabled when it is not necessary; 8After reset, hardware detection program memory space 0000H address is empty (ie #0FFH), then Automatically jump to the ISP function program entry address.

3 SM2965 memory structure

3.1 Program Memory

The SM2965 integrates 64k bytes of flash memory as program memory. The address range is 0000H to 0FFFFH, which is used to store the application program that executes the user program and the download program that executes the ISP function.

The download program space for executing the ISP function can be configured up to 4K bytes, the space size = N × 200H bytes, N=0 means that the download program is not configured, 64K bytes of Flash memory are all used for the application; N=1 means 0FE00H~ 0FFFFH has a total of 200H bytes for use in the download program space, from the 0000H to FDFFH supply program; N=8 indicates that the download program space reaches the maximum configuration, which is 4K bytes. The size of N can only be configured by the commercial programmer. Once configured on the programmer as N≠0, the configuration of the ISP space cannot be changed in the system. The SM2965 program space composition is shown in Figure 1. 0FFFFH-(N×200H) is the entry address of the download program.

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