[OpenOCD-user] SAML21 Chip erase

[melvin c. <mel...@gm...>]

I am trying to chip erase a SAML21 device which has been secured by setting
the security bit.

Reading the mailing list there is a reference to the SAMD chip erase -->
https://sourceforge.net/p/openocd/mailman/message/36116190/

I noticed the *at91samd chip-erase* command references register addresses that
are not correct for the SAML21.

SAMD code is :
#define SAMD_PAC1 0x41000000 /* Peripheral Access Control 1 */
#define SAMD_DSU 0x41002000 /* Device Service Unit */
#define SAMD_NVMCTRL 0x41004000 /* Non-volatile memory controller */
COMMAND_HANDLER(samd_handle_chip_erase_command)
{
struct target *target = get_current_target(CMD_CTX);

if (target) {
/* Enable access to the DSU by disabling the write protect bit */
target_write_u32(target, SAMD_PAC1, (1<<1));
/* Tell the DSU to perform a full chip erase.  It takes about 240ms to
* perform the erase. */
target_write_u8(target, SAMD_DSU, (1<<4));

command_print(CMD_CTX, "chip erased");
}

return ERROR_OK;
}

The SAML registers are:
#define SAMD_PAC1 0x44000000 /* Peripheral Access Control 1 */
#define SAMD_DSU 0x41002000 /* Device Service Unit */
#define SAMD_NVMCTRL 0x41004000 /* Non-volatile memory controller */

What's the best way to make this change? Is there a 'at91SAML chip-erase'
command?

Background Information.


I am using the FT232H with a UM232H module using the FTDI MPSSE.

You have to do a cold reset which is to hold the SWCLK line low while
removing the reset.

This I can do by running an openocd session which just holds the SWCLK and
rst lines low using ftdi_layout_init.
e.g.




*adapter driver ftdi#ftdi_device_desc "UM232H"ftdi_vid_pid 0x0403 0x6014*









*# data MSB..LSB       direction (1:out) MSB..LSB# 1111'1101'1111'1000
1111'1111'1111'1011ftdi_layout_init 0xfdf8 0xfffbftdi_layout_signal SWD_EN
-data 0ftdi_layout_signal SWDIO_OE -data 0x0800 -oe
0x0800ftdi_layout_signal nTRST -data 0x0100 -oe 0x0100ftdi_layout_signal
nSRST -data 0x0200 -oe 0x0200ftdi_layout_signal Reset -data 0x0400 -oe
0x0400*






*transport select swd# chip nameset CHIPNAME at91saml21j18set CPUTAPID
0x0bc11477source [find target/at91samdXX.cfg]reset_config none init*

I then start a new openocd session to action the chip erase.























*adapter driver ftditdi_vid_pid 0x0403 0x6014# data MSB..LSB
direction (1:out) MSB..LSB# 1111'1111'1111'1000
1111'1111'1111'1011ftdi_layout_init 0xfff8 0xfffbftdi_layout_signal SWD_EN
-data 0ftdi_layout_signal SWDIO_OE -data 0x0800 -oe
0x0800ftdi_layout_signal nTRST -data 0x0100 -oe 0x0100ftdi_layout_signal
nSRST -data 0x0200 -oe 0x0200ftdi_layout_signal Reset -data 0x0400 -oe
0x0400transport select swdset CHIPNAME at91saml21j18set CPUTAPID
0x0bc11477source [find target/at91samdXX.cfg] reset_config none initsleep
100at91samd chip-erasesleep 100exit*

With openocd in debug mode I get the error which shows openocd trying to
access the USB register and not the PAC.:










*Debug: 429 143 target.c:2482 target_write_u32(): address: 0x41000000,
value: 0x00000002Debug: 430 144 target.c:2523 target_write_u8(): address:
0x41002100, value: 0x10Debug: 431 145 ftdi.c:1211 ftdi_swd_switch_seq():
JTAG-to-SWDInfo : 432 145 adi_v5_swd.c:136 swd_connect(): SWD DPIDR
0x0bc11477Debug: 433 145 arm_adi_v5.c:653 dap_dp_init():
at91saml21j18.dapDebug: 434 146 arm_adi_v5.c:698 dap_dp_init(): DAP: wait
CDBGPWRUPACKDebug: 435 146 arm_adi_v5.h:506 dap_dp_poll_register(): DAP:
poll 4, mask 0x20000000, value 0x20000000Debug: 436 146 arm_adi_v5.c:706
dap_dp_init(): DAP: wait CSYSPWRUPACKDebug: 437 146 arm_adi_v5.h:506
dap_dp_poll_register(): DAP: poll 4, mask 0x80000000, value
0x80000000Error: 438 148 arm_adi_v5.c:438 mem_ap_write(): Failed to write
memory at 0x41000000Debug: 439 148 target.c:2528 target_write_u8(): failed:
-4*