Texas Instruments TMS320F20x/F24x DSP manual A.1.3 Erase Algorithm, SERA20.ASM, Preliminary, A-10

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