USB interface

USB interface for HRPT decoder

Note: decoder needs to be set to "6x2" mode.

wsat verion 2010.01 can communicate via this interface with the decoder.

pin left on schematic connect? description
+5V depends See chapter 'Power'
ctrl[7:0] Only if channel selection needed see chapter "Selection channels etc."
(no text, from RD of FT245R) Not if no channel selection needed TBD

DIO[7:0] Yes see table 1
is_out Only if channel selection needed TDB; connect to pin 63 buffer-FPGA = pin 14 par. port connector
rd_off If NO channel selection: to +5V see chapter "Selection channels
clk Yes see table 1
readyn Yes see table 1
r_clk_n Yes see table 1

pin left on schematic	connect?	description
+5V	depends	See chapter 'Power'
ctrl[7:0]	Only if channel selection needed	see chapter "Selection channels etc."
(no text, from RD of FT245R)	Not if no channel selection needed	TBD
DIO[7:0]	Yes	see table 1
is_out	Only if channel selection needed	TDB; connect to pin 63 buffer-FPGA = pin 14 par. port connector
rd_off	If NO channel selection: to +5V	see chapter "Selection channels
clk	Yes	see table 1
readyn	Yes	see table 1
r_clk_n	Yes	see table 1

HRPT-data from decoder to USB.

Next table shows which connections are needed to transfer the HRPT-data via USB to PC. If possible existing connectors on the decoder PCB are used. In a few occasions a connection needs to be made directly to a FPGA pin. Be aware that the ecoder PCB contains 2 FPGA's. The one near the EPROM contains the actual decoder; the other FPGA contains the data-buffer. This is the one to connect to the USB-interface. Naming in the left column of tables below means:
<pin-naam>@<connector_or_chip_name>
E.g..:

13@FPGA means: pin 13 of buffer-FPGA
17@CONP means: pin 17 of connector near parallelport
3@CON10 means: pin 3 of connector CON10

Tabel 1: Connection decoder with USB-interface: Data from decoder to USB.

decoder-PCB	USB-PCB	description
13@FPGA	r_clk_n	lees-klok
17@CONP	readyn	0=data in decoder
59@FPGA	D0	HRPT-data
3@CON10	D1	HRPT-data
2@CON10	D2	HRPT-data
1@CON10	D3	HRPT-data
3@CON9	D4	HRPT-data
1@CON9	D5	HRPT-data
3@CONP	D7 (!! See note below!!)	!!!Via R=100 ohm!!!
9@EPROM	clk	666/1300 kHz

NOTE: Use fixed wsat release 2010.01.a.
For earlier release 2010.01, "3@CONP" needs to be connected to "D6" instead of "D7".

Table 2: Connections in decoder

decoder-PCB	Connect with	description
69@FPGA	GND	set to 2x6 mode
2@CON9	3@CONP	connect r_clk with rdy_nib

Selection channels etc.

If channel selection/decoderselection isn't needed via PC then this part can be kept very simple. In fig. 1 IC 74273 isn't needed, and pin "rd_off" must be connected to +5V. This prevents that the USB chip will drive the data lines. For further adaptions see table 3.

Tabel 3: No channel selection by PC (all channels active)

decoder-PCB Connect with Description
18@CONP GND output always active
1...6 @CON1 to +5V all channels active
jumper CON2 pin1-2 remove manual selection 'on'

decoder-PCB	Connect with	Description
18@CONP	GND	output always active
1...6 @CON1	to +5V	all channels active
jumper CON2 pin1-2	remove	manual selection 'on'

Power.

There are a few possiblilities to power USB-interface and decoder with +5V. The USB-connector contains 5V, from PC, which can be used to power both interface and decoder. As a result the decoder is always powered if PC is on (and decoder is connected to PC).
Possibilities are:

power	to do	comments
Power USB-interface and decoder from USB	Add jumper J1 (fig. 1) Remove jumper J3 (fig. 1) Connect 5V-pin to 5V decoder Don't connect an external power unit to decoder!	Disadvantage: decoder altijd On if PC is on.
Power USB-interface and decoder from decoder	Remove jumper J1 (fig. 1) Add jumper J3 (fig. 1) Connect 5V-pin to 5V decoder Use power unit decoder	recommended
Power USB-interface from USB connector Power decoder using it's own power unit	Add jumper J1 (fig. 1) Remove jumper J3 (fig. 1)	Disadvantage: "false" currents if decoder is powerd and USB not or vice versa

About last possibility: The "false currents" go via the connections between USB-interface and decoder. As a result decoder-LEDs may go 'On' while decoder isn't powered. It is possible that after some time decoder and/or USB chip will degrade.