How to just use TTL puart in TAG3 without through USB?

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Anonymous
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I have read MMP920737TAG03-HWUM100-R.pdf, I know that TAG3 have a USB port and it can simulate two com ports on PC, one is HCI, the other is puart.

Through USB, HCI and PUART work fine. But I have an idea that use PUART TX and RX pins which are TTL level. After checking the MMP920737TAG03-HWUM100-R.pdf, on GPIO header, I found that J7 Pin 5 and J8 Pin 1 are PUART TX and RX. I also found that I should switch SW4 pos5~6 to OFF to make PUART disconnect with USB module. Then, I use my TTL2USB cable to connect with J7 pin5 and J8 pin 1, but I can't get anything through tera term4.83. But after switch SW4 pos5~6 to ON, I can data output and input work normal through USB port.

So, what extra action should be taken if I want to use PUART pin32 and pin33 which do not connect with USB port?

BTW, my TTL2USB cable is this one: http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm

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1 Solution
Anonymous
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Resolved this issue.

I initial PUART_RX as pin25 which should be pin32.

View solution in original post

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7 Replies
Anonymous
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Hello Kristen,

Tera Term should work as long as you configure it for your COM Port and Serial port settings.

Have you set up PUART on those pins?

How to set up PUART flow control?

Lots of posts on setting up PUART:

Not sure it answers your question, but...

For simplicity sake, look at the iBeacon Reference design that has NO FTDI device

In this case, we are programming the device WITHOUT a USB FTDI device

Take a look at what we did for our simple Beacon Reference Design:

iBeacon BCM20737 Reference Design PDF Schematic (SOC)

iBeacon BCM20737 Reference Design Overview

Here is the board with a cable

CoB_Design_sm.jpg

NOTES: This is a SPECIAL FTDI cable with 3.3V power output

pastedImage_0.png

CoB_Design_Pins.JPG

We used at 3.3V Supply part below so we could connect directly to the 3V supply of our board

Let me think of a few more direct answers to your question

Thanks,

JT

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Anonymous
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Hi JT,

My USB cable is same with your ibeacon reference design, I think cable work fine.

What I want is to use TAG3 PUART to connect with another MCU through UART interface. Before doing that, I use USB2TTL cable to test it whether PUART work fine or not when it disconnect with TAG3 USB port but connect wit USB2TTL cable.

The result is that I can't get anything from USB2TTL cable, but when I connect PUART with TAG3 USB, I can get something. This is what I concern.

The PUART pins is P32 and P33 which is the same with SDK2.2 PUART_CONTROL.

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Anonymous
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Kristen,

What application are you running to ensure that PUART is configured and that you have data transmission?

Search the community for puart_control:

pastedImage_0.png

Thanks

JT

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Anonymous
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Hi JT,

I know how to initial PUART peripheral, and I think my PUART module work fine because I can use puart_write() function to output string through FT2232 which can simulate two COM port on laptop. Likewise, I can get PUART interrupt callback handler when I sent some characters from laptop to PUART.

But when I disconnect with FT2232, and use USB2TTL cable, the result is failure. puart_write() and interrupt callback function can't take effect.

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Anonymous
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Hello Kristen,

1.  Are you getting the correct voltage levels from your FTDI cable?

2.  After you removed the FTDI device from the board, have you checked the 3V Supply rail?

3.  Are you getting any signals on the P32 and P33 at all?

JT

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Anonymous
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Resolved this issue.

I initial PUART_RX as pin25 which should be pin32.

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Anonymous
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Great news!

JT

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