Thanks Sascha for your answer,
I saw this link: https://www.schach-computer.info/wik...ag_Sapphire_II
and sapphire II runs at even faster frecuency 32 Mhz. So maybe sapphire I did have two different models that operates at different frecuencies maybe the best way with out oppening is to make the BT tests as you wrote. Some minutes ago i found out that the problem to use the citrine board with the sapphire is the different baud rate that they have. Citrine uses 56.700 baud and sapphire uses 9.600 baud. Is there any bud rate converte in the market?. Has any use one of them?

best regards
Ricardo