Reg: Start up sequence of the HL6528

IoT Modules Legacy HL Series
1

Hi guys,

We integrate HL6528 with LPC1756 using UART1. 3.3V power given to VBATT, VBATT_PA and VBATT_PA.

PWR_ON pin is pulled down to Zero using output of LPC1756.

While transferring the AT data from LPC Tx, there is no change in the Tx line (Checked with CRO)

But after power-up the HL6528, CTS line showing spike always. CTS is not settle down to low(0) after few seconds.

There is no response in Rx and Tx of the Modem.

Kindly help us to identify the issue.

Thanks in Advance

2

Hi,

we also stucked on that. There is no real descripton, but we pulled the DTR low, an than it works.

Best regards,
Remo Reichel
solvimus GmbH
www.solvimus.de

3

Hi Remo,

Yes. You are correct.

Previously we have problem in the power supply of the Modem. After modification in circuit we can able to receive the data from Modem but not able to transmit.

After pulling the DTR pin to zero, we can able to transmit and receive data from the Modem. :slight_smile:

Thanks for your help.