design and test of a data acquisition system based on usb interface for the medipix2 chip
DESCRIPTION
Università di Cagliari. Sezione di Cagliari. Design and test of a data acquisition system based on USB interface for the Medipix2 chip. V. Fanti, R. Marzeddu, G. Piredda, P. Randaccio. System outline. Medipix2 serial readout port Universal Serial Bus v 1.1 interface - PowerPoint PPT PresentationTRANSCRIPT
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IWORID2004 Glasgow 1
Design and test of a data acquisition system based on USB interface for the
Medipix2 chip
Università di CagliariSezione di Cagliari
V. Fanti, R. Marzeddu, G. Piredda, P. Randaccio
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IWORID2004 Glasgow 2
System outlineSystem outline
DemonstratorUSB 1.1
(1.5 MBits / s )
• Medipix2 serial readout port
• Universal Serial Bus v 1.1 interface
• External power supply card
• Reduced size (3.8 x 4.8 cm2)
• No extra interface board needed
• Acquisition time ~ 1 s
Power supply card
+ 2.2 V + 50 V
220 V
Host PC
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IWORID2004 Glasgow 3
General featuresGeneral features
• Serial readout of Medipix2 chip
• Test pulse input
• Readout of Medipix2 internal DACS with an 8-bit ADC
• USB v. 1.1 low speed interface (data rate up to 1.5 Mbits/s)
• Reduced size (3.8 × 4.8 cm2)
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IWORID2004 Glasgow 4
Project overviewProject overview
•One Medipix2 readout chip
•One Microchip PIC16C675-I/NP microcontroller
• USB v. 1.1 interface (up to 1.5 Mbits/s)
• one channel 8-bit ADC for internal DACs readout
• Bidirectional Serial Communication Interface between PIC and Medipix2 chip
• Two LVDS driver/receiver (DATA_IN/OUT, FCLOCK_IN/OUT signals)
• One voltage ref. circuit for internal DACs reference (1.324 V)
• Three power lines: 2.2 V, 50 V (adj), 5 V (USB)
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IWORID2004 Glasgow 5
Something about USB …Something about USB …
1.5 Mbit/s means a readout time equal to ~600 ms
1. USB stands for Universal Serial Bus
2. Data rate supported:
- (v 1.1 ) 1.5 Mbit/s (low speed) - 12Mbit/s (high speed)
- (v 2.0) 12Mbit/s (full speed) - 480Mbit/s (high speed)
3. USB controller is required to control bus and data transfer.
4. Plug &Play and Hot-Swap connection
5. Cable up to 5 m (4-wire cable).
6. Up to 127 devices supported.
7. Power supply to external devices is 500 mA/5V (max).
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IWORID2004 Glasgow 6
Something about Something about PIC16C765PIC16C765
1. USB Connectivity 1.1v (Low Speed)
2. 8-bit microcontroller 24 MHz int. frequency
3. 5 channels of 8 -bit Analog-to-Digital converters
4. Serial communication interface (USART)
5. Program memory size = 14336 bytes
6. RAM size = 256 bytes
7. CMOS One Time Programmable (OTP) !
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IWORID2004 Glasgow 7
An easy-to-use systemAn easy-to-use system
A personal computer
Plug & Play device – The demonstrator is auto detected from the PC like as a general HID device
HID = Human Interface DeviceDemonstrator
Power cable
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IWORID2004 Glasgow 8
Demonstrator card Demonstrator card
• Flexible and easy connection
• Based on a single chip PIC Microcontroller
• Reduced size (dental application ?)
Top side
Bottom side
2.2V, 50 V cable2.2V, 50 V cableUSB cableUSB cable
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IWORID2004 Glasgow 9
Block diagramBlock diagram
LVDS CMOS
DS90LV019TM
PIC16C765
To host PC
USB interface
Serial Synchronous
Interface
SHUTTERRESETM1M0ENABLE_OUTCSPARE_FSRPOLARITYENABLE_INC
8-bit register
VusbD+D-
ADC 8-bitDAC_OUT
DATA
Med
ipix
2 ch
ip
1.324 V
PFCLOCK_OUT
NFCLOCK_OUT FCLOCK_OUT
CMOS LVDS
PFCLOCK_IN
NFCLOCK_INCLOCK
CMOS LVDSNDATA_INDATA_IN
PDATA_IN
LVDS CMOS
PDATA_OUT
NDATA_OUT DATA_OUT
TX/RX#
CLOCK
TP
DAC_BIAS
8
1
VCC (+5V)
1
1
1
+5 V
+50 V
+2.2 V
3
Power filters
TEST_INTP
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IWORID2004 Glasgow 10
The power supply cardThe power supply card
220 V – 50 Hz power plugged
50 V (adj.) – 100 A output for sensor polarization
2.2 V - 1 A output for Medipix2 chip power supply
220 AC 2.2 V – 1 A
~50 V – 100 A
Transformer Rectifier circuit
5 V =
DC-DC converter circuit5 V =
Voltage regulator
Power Supply Card
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IWORID2004 Glasgow 11
Some questions… Some questions…
So why USB v 1.1 ?
Microchip does not yet produce microcontrollers with USB 2.0 interface
Why do we need an external power supply card ?
The maximum current intensity which USB power line can supply is 500 mA.
Why such a little card?
We think it is a good opportunity so use this project for some special applications (ex. dental radiography?)
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IWORID2004 Glasgow 12
Project schematicProject schematic(Orcad(Orcad Capture)Capture)
PIC
Medipix2
LVDS
DAC biasPower filter
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IWORID2004 Glasgow 13
Layout Layout (1)(1)
Eight layers board:
• Top layer: components
• Bottom layer: Medipix2 chip
• Inner layer 1: routing
• Plane layers VCC (5 V), GND
• Plane layers VDD, VDDA, VDDA LVDS (2.2V)
Dimensions: 4.8 × 3.8 cm2 (H × W)
(Orcad(Orcad Layout) Layout)
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IWORID2004 Glasgow 14
Layout Layout (2)(2)
LM385
DS90LV019TM DS90LV019TM
PIC16C765-I/PT
6 M
Hz
quar
z
VDDLVDS filter
VDDA filter
VDD filter
VCC conn
USB conn
Medipix2 chip
PIC16C765-I/PT
TOP BOTTOM
Caps
Caps
Caps
Caps
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IWORID2004 Glasgow 15
Prototype cardPrototype card
• Reproduce the demonstrator board on larger scale ( 15 × 20 cm2)
• All components are mounted on a prototype board and connected
by wire wrap technique
• Medipix2 chipboard with 128 pin DIL connector
• PIC16C765 with 44 DIL package (reprogrammable!)
Prototype card layout
Medipix2 Chipboard
DS90LV019
PIC16C765
LM385
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IWORID2004 Glasgow 16
The simplest and cheapest Medipix2 interface
We are testing another interface competitive to the USB one: the parallel port
Three software-controlled registers:
• Data register: 8 bits I/O
• Control register: 4 output bits
• Status register: 5 input bits
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IWORID2004 Glasgow 17
Interfacing Medipix2 with parallel Interfacing Medipix2 with parallel portport
Why parallel port?
- Available in all PCs
- Easy to use and to debug
- Enough I/O lines to fit requirements of Mpx2
- No other electronics needed (just three LVDS-CMOS converters)
But:
- Slow (1 – 5 s acquisition time)
- Deserialization and derandomization must be done by software
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IWORID2004 Glasgow 18
Using the parallel port registersUsing the parallel port registers
- Data register
Used to define the I/O operation modes
Parallel port DR
Medipix2 control lines
D0 M0
D1 M1
D2 RESET
D3 SHUTTER
D4 EN. TPULSE
D5 POLARITY
D6 SPARE FSR
D7 ENABLE_INC
- Control register
Used to send clock and serial data
Parallel port DR
Medipix2 control lines
C1 FCLOCK*
C3 DATA_IN*
*Through CMOS – LVDS converter
- Status register
Used to read serial data and status bit
Parallel port DR
Medipix2 control lines
S3 DATA_OUT*
S4 ENABLE_OUTC
*Through LVDS – CMOS converter
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IWORID2004 Glasgow 19
In spite of its simplicity it works!
Shadow of a lead filter (X-ray 50 kV)
Sr 90 beta source pointing on the upper right corner