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Microcontrollers ApNote AP1652
: Additional file AP165201.EXE available
Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
C163-16F Flash devices have no internal boot ROM and therefore no bootstrap loader which is needed for in-system programming of virgin Flash in single chip applications. From design step Bx on C163-16F Flash devices provide a mechanism for switching the reset vector depending on PORT0 configuration. This application note gives hints and examples how this feature can be used to achieve bootstrap loader support on C163-16F Flash. Author : Peter Kliegelhofer / HL DC AT Microcontroller Application Support
Semiconductor Group
07.98, Rel 01
Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
Contents 1 2 3 4 5 6 A B C
Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pre-programming the internal user Flash. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Important hint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Bootstrap loader activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Bootstrap loader handing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C163.A66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C163.ILO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C163.BAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 7 7
AP1652 ApNote - Revision History Actual Revision : 07.98 Page of Page of actual Rev. prev.Rel. Previous Revision : none (Original version)
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Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
1
Introduction
In general a bootstrap loader is used to load startup code and/ or Flash programming routines from a remote code source via a serial interface without requiring additional external boot memory. On most C16x microcontrollers a bootstrap loader code is usually stored in a special internal bootROM (or equivalent non-volatile memory section). However, such a bootstrap loader code memory is not available on C163-16F. From design step Bx on C163-16F devices provide a mechanism for switching the reset vector depending on PORT0 configuration. This feature can be used to achieve bootstrap loader support on C163-16F Flash. For this it is necessary to pre-program the user Flash with a bootstrap loader code. On one hand this can be done by the user himself. On the other hand Siemens reserves the option to deliver pre-programmed C163-16F Flash devices in the future with a special marking text. This application note gives hints and examples how to prepare C163-16F Flash devices for bootstrap loader functionality. 2 Pre-programming the internal user Flash
From design step Bx on two different start addresses can be selected after reset when pin EA is pulled "high", depending on PORT0 configuration. The start address is 00'0000h 02'0000h when P0L.4 is pulled "high" or left open during reset or when P0L.4 is pulled "low" during reset.
Basically these address areas are covered by internal Flash memory. Single chip mode ( = internal Flash enabled) is entered, when pin EA (external access) is "high" during reset. Mapping of the physical Flash address 00'0000h to the logical address 00'0000h (which concerns the lowest 32K block of the internal Flash memory) depends on bit "ROMS1" in register SYSCON. With ROMS1 = 0 the lowest 32K of internal Flash are mapped to segment 0 (00'0000h...00'7FFFh). Because the interrupt vector table addresses (which are very important for every user program) point to the lowest addresses of segment 0, the BSL code must be stored in segment 2. Since a virgin C163-16F Flash device has no on-chip bootstrap loader, it is necessary to use a hardware system which enables booting from external memory, for instance the Ertec EVA163 evaluation board or the Phytec C163 starter kit. In the appendix there is a tested bootstrap loader (BSL163) which can be programmed into the internal user Flash. In-system programming of on-chip Flash/ OTP memory is supported by the memory programming tool "Memtool" which is also part of this application note.
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Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
3
Important hint
Assuming that there is a pre-programmed C163-16F Flash device, already soldered on PCB, well prepared for in-system programming end-of-line. * It must be considered that the bootstrap loader code resides unprotected in the internal Flash memory at location 02'0000H, which is the bottom of Flash sector 2 (figure 1). * Care has to be taken when erasing or programming the Flash memory. Especially it is important to know, that there is no way to reboot the C163-16F Flash without external memory, if sector 2 of the internal Flash memory is erased and there is no valid boot code in sector 0. 4 Bootstrap loader activation
Pin P0L.4 activates the bootstrap loader by code fetches to location 02'0000 H, when "low" during reset and when pin EA is "high". The bootstrap loader at this location may then, as in the example program BSL163, loads the start code into the internal RAM of the C163-16F Flash via the serial interface ASC0. The main effect of pin P0L.4 beeing "low" during reset is that it changes the reset value of the code segment pointer CSP from 00 H (default) to 02H. In this case the internal program will be started at 0000H in segment 2, with ROMS1 = '0' and EA = 'high" at reset time. Design step BA is the first step which offers the possibility for switching the reset vector. Therefore the described bootstrap loader functionality is not implementable on earlier steps (AA, AB). By default the C163-16F Flash starts fetching code from location 00'0000H, the bootstrap loader is off. 5 Bootstrap loader handling
Because the bootstrap loader resides in the normal accessable Flash memory , there is no protection against unintentional erase. Furthermore the user has to take care not to erase sector 2 until a valid and bootable application code has been programmed successfully to sector 0. A possible boot flow" for the C163-16F Flash without external memory could be:
* Booting by pulling P0L.4 "low" and EA = "high" (selects the bootstrap loader in sector 2 of the * * * * *
Flash memory), Provide 16 words of second level bootstrap code at the serial interface (see file "BSL163" in the appendix), Start of the 16 words out of the internal RAM (done automatically by the bootstrap loader), (Probably) loading a third level bootstrap routine via the serial interface into the internal RAM, Programming sector 0 of the Flash memory with the desired application program (probably by download via the serial interface), Reset of the C163-16F Flash by pulling P0L.4 "high" (selects the previously programmed code in sector 0 of the Flash memory), test for proper function of the code in sector 0, this code should always support program download via the serial interface and execution out of the internal RAM, Programming of the other sectors of the Flash memory; it is recommended to leave the bootstrap loader in sector 2, i.e. to rewrite it in the case that sector 2 has been erased.
*
Note: Flash command sequences always must be executed from locations outside the Flash memory.
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Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
Page 11 Segment 2 Page 10 Page 9 Page 8 Page 7 Segment 1 Page 6 Page 5 Page 4 Page 3 Segment 0 Page 2 Page 1 Page 0 C163-16F Memory Configuration
02'FFFFH 02'C000H 02'8000H 02'4000H 02'0000H 01'C000H 01'8000H 01'4000H 01'0000H 00'C000H 00'8000H 00'4000H 00'0000H 128 KByte Flash Memory Sector 0 (0 - 32 K) Sector 0 (0 - 32 K) Sector 1 (32 - 64 K) (32K) Sector 2 (64 - 96 K) (32K) Sector 3 (96(32K) K) - 128
01'FFFFH
01'8000H BSL 01'0000H
00'8000H
Mapping
00'0000H
Physical Flash Address
Figure 1 Location of the Bootstrap Loader on C163-16F The bootstrap loader on C163-16F resides in the Flash memory at address 02'0000H (physical Flash address 01'0000H) in the case of the example "BSL163" and occupies less than 100 Bytes. 6 Miscellaneous
The acknowledge Byte (ID Byte) of the attached bootstrap loader is D5H". It is recommended to leave the BSL code in Flash sector 2. In his application software the user must reserve this Flash memory area (address range between 02'0000h and 02'007Fh). Due to this fact the first address in Flash sector 2 which is freely available for user software is address 02'0080H. Remember that erase can only be executed sectorwise. Note: For further information concerning bootstrap loading please refer to application note AP1607 Bootstrap Loader C165/ C167".
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Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
Appendix A
;---------------------------------------------;# Name: BSL163.A66 ;# Version: 1.0 ;# Function: C163 Flash Bootstrap Loader ;# Memory: Internal Flash ;# Author: Peter Kliegelhoefer ;# Date: 21.10.1997 ;# (C)1997 SIEMENS AG ;---------------------------------------------$segmented name bsl163 aux section data at0FA40h RamRoutineStartlabel word StartAddressds 32 aux ends SYSRAM DGROUP aux, SYSTEM ASSUME DPP3:SYSRAM RBank REGDEF SSKDEF 1 MAINCODE section code MAINPROC proc TASK ;----------------------------------------------------------------------------;* Bootstrap Loader: Receives 32 bytes via serial port 0 and stores them * ;* into the internal RAM. Afterwards it performs a jump to the beginning of * ;* the loaded RAM area (0FA40h) and executes the loaded data as a program. * ;----------------------------------------------------------------------------EndAddress equ StartAddress + 31 ; End Address of RAM Area Ack_byte equ 0D5h ; Acknowledge Byte of Bootstrap Loader ;----------------------------------------------------------------------------BSL_INIT: ; don't load syscon or buscon ! DISWDT ; disable watchdog timer MOV SP,#0FC00h ; set stackpointer MOV STKUN,#0FC00h ; set stack underflow pointer MOV STKOV,#0FA00h + 6 ; set stack overflow pointer MOV CP,#0FC00h ; set registerbank WaitStartBit: JB P3.11,WaitStartBit ; wait for start bit at RXD0 BSET T6R ; start timer T6 WaitStopBit: JNB P3.11,WaitStopBit ; wait for stop bit at RXD0 BCLR T6R ; stop timer T6 MOV MDL,T6 SUB MDL,#36 ; rounding & adjustment MOV R1,#72 ; baudrate = (T6 / 72) - 1 DIVU R1 InitSerialPort: MOV S0BG,MDL ; load baudrate generator BSET P3.10 ; initialize TXD0 output BSET DP3.10 MOV S0CON,#8001h ; initialize serial port 0: ; 8-bit data, no parity, one stop bit ; receiver not started: single wire option SendAcknowledge: MOV S0TBUF,#Ack_byte ; send acknowledge byte for baudrate check WaitTransmOver: JNB S0TIR,WaitTransmOver ; wait till end of transmission BCLR S0TIR ; clear transmit interrupt request flag BSET S0REN ; receiver enabled ReceiveData:
;
1 = 0FB00h-0FBFFh
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Bootstrap Loader Support on C163-16F Flash Devices (Bx-step)
MOV R0,#StartAddress ReceiveLoop: JNB S0RIR,ReceiveLoop MOVB [R0],S0RBUF BCLR S0RIR CMPI1 R0,#EndAddress JMPR CC_NE,ReceiveLoop JMPS 0,RamRoutineStart retv MAINPROC MAINCODE end endp ends
; ; ; ; ; ; ;
wait for receive interrupt request store received byte clear receive interrupt request flag all bytes received ? if not, continue loop yes: jump to RAM routine dummy
Appendix B
;--------------------------------------------;# Name: BSL163.ILO ;# Function: Input Locator File ;# (C)1997 SIEMENS AG ;--------------------------------------------TASK bsl163.lno NOVECINIT NOVECTAB ad (se(MAINCODE(0020000h)))
Appendix C
@echo off rem ----------------------------------------rem Name: BSL163.BAT rem Function: Batchfile for generating the rem C163 Flash Bootstrap Loader rem Toolchain: Tasking tools V5.1 rem (C)1997 SIEMENS AG rem ----------------------------------------@echo on
a166 bsl163.a66 nomod166 extend stdnames(reg163.def) l166 bsl163.obj l166 @bsl163.ilo to bsl163.out nowa(141) ihex166 -l16 -i16 -obsl163.hex bsl163.out
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AP1652 07.98

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