Using Serin/Serout with USB lead

[cpedw]

I have cobbled together a circuit similar to the Datalogger module AXE110 using the AXE091 development board. This all worked fine; I used the wizard to write a program; collected data using Datalink and all was well.
Then I changed from a serial connection to USB. The download works OK so I have set up the USB connection right I think. But I can't use the Datalink utility to transfer data. The wizard uses
serin 6, N4800, ("G")
and
serout 7,N4800 ...

to receive a prompt and send data. Why won't it work through the USB connection?
Thanks,
Derek

 

[Andrew Cowan]

Are you using an Axe027 download cable?

A

 

[cpedw]

Yes, I'm using the AXE027 for USB download/transfer; the AXE026 for serial port operation. SHould also mention the chip is an 18x.
Derek

 

[Technical]

So you are using the 3.5mm jack socket at the bottom of the board for the serial connection? Which PICAXE pins have you jumpered across to the N side TX and RX pins on the RS232 connection point?

 

[cpedw]

So you are using the 3.5mm jack socket at the bottom of the board for the serial connection? Which PICAXE pins have you jumpered across to the N side TX and RX pins on the RS232 connection point?

That's right. I use the midle connector on the side for programming - that seems to wok with USB and serial cables, then move to the bottom jack socket for data transfer.
The connections are:
N-TXD - leg 13, output7
N-RXD - leg 15, Input 6.

Here are the relevant bits of code (from the Datalogger wizard):
'Wait for G character sent from software
serin 6, N4800, ("G") 'Wait for GO signal
and
'transmit data
tx_data:
serout 7,N4800,(#address,COM,#data0,COM,#data1,COM,#data2,COM,#data7,RET,LFEED)

 

[Technical]

All correct, should work! The two socket circuits are identical, so assuming no pcb damage, there is no reason why one should work and the other not!

 

[cpedw]

Problem solved (well sort of). I found that the reason why it wasn't working is that I had connected one of the Digital Input Switches in parallel with the Serial Input on Input 6. That was to allow its use as an Interrupt.
I see from the datasheet that the switch has a 10k resistor to 0V, similar to the Download circuit. It's surprising that it prevents Serin from working with the USB cable but the Serial cable is happy to allow it.

 

[Technical]

This 10k would be on the PICAXE (not computer) side of the 22k. That is why it would not work.