16
revolution
(c) Revolution Education Ltd. Email: [email protected] Web: www.picaxe.co.uk V2.2 02/09
AXE027.PMD
PICAXE USB CABLE
x
x
x
x
x
PICAXE
serial out
serial in
0V
22k
10k
Above view
100
100n
100
4.7u
100n
AXE027
PICAXE
USB Cable
(c) 2006
FB
10n 47p 47p
1 18 19 16
4 17 20 24 26
15
14
32
8
30
2
2x
10k
FT232RQ
USB A
+
3.5mm
TXD
RXD
OV
7.0) PICAXE Download Circuit
The standard PICAXE download socket (part CON039) and 10k/22k download circuit is unchanged for use with the
AXE027 USB cable (ie the same circuit is used for both the AXE026 serial cable and the AXE027 USB cable).
As the AXE027 interfacing voltage is at true logic levels (5V, rather than RS232 voltage levels) it is theoretically
permissible to reduce the value of the 22k resistor (e.g. to 1k), but only
if
a AXE026 serial cable is
never
to be used.
However for maximum versatility it is recommended to leave the circuit unchanged.
There is no advantage to using the ‘enhanced’ download circuit (see main PICAXE manual) with the AXE027 USB
cable, as the enhancements in this circuit are to compensate for negative variations in RS232 voltages (which do not
apply when using the 5V logic level AXE027 USB cable). However, if already built into a project board, it is
acceptable to continue to use the enhanced circuit.
The AXE027 USB cable may also be used to transmit/receive serial data from the PICAXE input/output pins (via serin
and serout commands).
6) AXE027 Circuit Diagram
The miniature USB to serial circuit is built into the plastic moulding of the USB plug on the AXE027 cable. The circuit
diagram is shown below.
