What is the exact expected sequence for the YMODEM protocol used in IAP and SBSFU?

[EWieb.1]

Hello,

for some STM32 controllers ST offers for application-update the IAP and SBSFU modules:

https://www.st.com/en/embedded-software/x-cube-iap-usart.html

https://www.st.com/content/st_com/en/products/embedded-software/mcu-mpu-embedded-software/stm32-embedded-software/stm32cube-expansion-packages/x-cube-sbsfu.html

In both the YMODEM protocol used.

In the ST documentation the ymodem protocol is described very short in this way:

The Ymodem protocol sends data in 1024-byte blocks. Error detection is applied to data

blocks transmitted to the STR91xFA internal RAM. This is done through a comparison

between the transmitted and received data. Blocks received unsuccessfully are

acknowledged with a NAK (Negative Acknowledgement). For more details about the

Ymodem protocol, please refer to the existing literature.

What exactly does ST mean? What is the exact expected sequence?

Do you mean like described in 

http://www.blunk-electronic.de/train-z/pdf/xymodem.pdf

on page 16, Figure 3

Is this the expected sequence? 

Thanks and BR

EW

[Pavel A.]

Yes this is more or less the sequence, Are you having any problem with ymodem? Maybe, using teraterm?

-- pa

[EWieb.1]

It seems to be in this way: