UM10139

UM10139Chapter 21: Flash Memory System and ProgrammingRev. 01 — 15 August 2005User manual21.1 Flash Boot Loader21.2 Features21.3 Applications21.4 DescriptionThe Boot Loader controls initial operation after reset, and also provides the means toaccomplish programming of the Flash memory. This could be initial programming of ablank device, erasure and re-programming of a previously programmed device, orprogramming of the Flash memory by the application program in a running system.• In-System Programming: In-System programming (ISP) is programming orreprogramming the on-chip flash memory, using the boot loader software and a serialport. This can be done when the part resides in the end-user board.• In Application Programming: In-Application (IAP) programming is performing eraseand write operation on the on-chip flash memory, as directed by the end-userapplication code.The flash boot loader provides both In-System and In-Application programming interfacesfor programming the on-chip flash memory.The flash boot loader code is executed every time the part is powered on or reset. Theloader can execute the ISP command handler or the user application code. A a LOW levelafter reset at the P0.14 pin is considered as an external hardware request to start the ISPcommand handler. Assuming that proper signal is present on X1 pin when the rising edgeon RESET pin is generated, it may take up to 3 ms before P0.14 is sampled and thedecision on whether to continue with user code or ISP handler is made. If P0.14 issampled low and the watchdog overflow flag is set, the external hardware request to startthe ISP command handler is ignored. If there is no request for the ISP command handlerexecution (P0.14 is sampled HIGH after reset), a search is made for a valid user program.If a valid user program is found then the execution control is transferred to it. If a valid userprogram is not found, the auto-baud routine is invoked.Pin P0.14 that is used as hardware request for ISP requires special attention. Since P0.14is in high impedance mode after reset, it is important that the user provides externalhardware (a pull-up resistor or other device) to put the pin in a defined state. Otherwiseunintended entry into ISP mode may occur.21.4.1 Memory map after any resetThe boot block is 12 kB in size and resides in the top portion (starting from 0x0007 D000)of the on-chip flash memory. After any reset the entire boot block is also mapped to thetop of the on-chip memory space i.e. the boot block is also visible in the memory regionstarting from the address 0x7FFF D000. The flash boot loader is designed to run from this© Koninklijke Philips Electronics N.V. 2005. All rights reserved.User manual Rev. 01 — 15 August 2005 291