I recently got some CH559T (SSOP20) via Amazon. It seems I got old stock because they have a bootloader v2.0.

It seems this loader does not start on a empty flash. Took me a while to realize that. Then I get a strange verify error when flashing a app with ISPTool V3.2. I also can not switch the Cfg Pin to P5.1 (D+)

Message:

Verify...

Wrong head offset 0x00001BC0

Qestions:

- can V2.0 use D+ as a bootloader Pin?

- why doesnt the bootloader start on an empty flash (never see that before)

- What does the error msg mean? The app still flashes correctly and can run.

This error indicates that the hardware actively returned an error code while the ISP was verifying a packet. This boot version is too old and no longer supported by the latest ISP tools, it is recommended to replace it with the latest version of the chip.

ok I sniffed the USB trafic... Bootloader 2.0 is a derivat of the old 1.1 loader. The problem ist the last verify packet.

The WCH ISP tool does not fill that packet to minimum verify blocksize (0x10  if i remember correctly).

BTW its the same with older tool versions. Thats clearly a bug in WCHISPTool.