ST7538 tx-lock

[drumfire]

Posted on April 13, 2006 at 11:20

ST7538 tx-lock

[drumfire]

Posted on March 22, 2006 at 04:19

Hi all,

I'm developing a control system using ST7 & ST7538.

In some cases (when power supply in not so good), the ST7538 will receive data correctly (then the register is ok) but refuses to transmit. Even after a register re-programming. I check all the lines and all works fine.

Do you know if there is a tx-lock feature (other the tx-timeout one)?

Do you know how the modem can be reseted?

Many thanks in advance,

Patrik

[drumfire]

Posted on March 22, 2006 at 06:55

Is it maybe related to UVLO (Under Voltage Lock Out) modem feature?

[drumfire]

Posted on March 23, 2006 at 10:25

I see that after Power Good goes down for a while (Vdc falls under 4.3V) the modem will lock the transmissions (but not the receiving).

Even after Vdc returns at 5V, the modem refuses to transmit.

The signal REGOK is always low (ok).

Does somebody know why of this behaviour and how to restore normal operation?

Thanks,

Patrik

[drumfire]

Posted on April 13, 2006 at 11:20

You are right Emile :-). We only need to stop WD signal to toggle (for more than 1.5s), when PG signal falls down. This will cause, in our hw, a global system reset.

Thank you very much for your support,

Patrik