Texas Instruments TMS320F20x/F24x DSP manual Erase Algorithm, SERA20.ASM, Segst

Assembly Source for Algorithms

PRELIMINARY

A.1.3 Erase Algorithm, SERA20.ASM

This code is an implementation of the erase algorithm described in section 3.3 on page 3-10.

Memory section: fl_ers

Entry point: GERS

Parameters to be declared and initialized by the calling code are:

-PROTECT defines the values of bits 8±15 of SEG_CTR during the erase algorithm.

-SEG_ST defines the start address of the flash array to be erased.

-SEG_END defines the end address of the flash array to be erased.

Return value: ERROR (@BASE+15); 0 = Pass, 1 = Fail

**************************************************************

*	ERASE subroutine	**
*		**
*	TMS320F2XX Flash Utilities.	**
*	Revision: 2.0, 9/10/97	**
*	Revision: 2.1, 1/31/98	**
*		**
*	Filename: sera20.asm	**
*		**

*Called by: c2xx_bex.asm or flash application programs. **

* **

*!!CAUTION ± INITIALIZE DP BEFORE CALLING THIS ROUTINE!! **

*			**
* Function: Erases one or more contiguous segments of			**
*	flash array 0/1 as specified by the		**
*	following variables.		**
*	SEG_ST	Segment start address	**
*	SEG_END	Segment end address	**
*	PROTECT	Sector protect enable	**
*			**
* The algorithm used is XOR±VER1, which means that in			**

*addition to the VER1 read mode, an XOR readback is used **

*	to gain more margin. During the read portion of the	**
*	erase, two reads are performed for each address; for the **
*	first read, all address bits are complemented using a	**
*	logical XOR with the array end address. The data read	**

*during the first read is discarded, and the second read **

* is performed on the actual address. This scheme		**
*	simulates the worst±case branching condition for code	**
*	executing from the flash array.	**

A-10 PRELIMINARY