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
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
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
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)
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)
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).
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) !
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
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
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
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
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?)
IWORID2004 Glasgow 12
Project schematicProject schematic(Orcad(Orcad Capture)Capture)
PIC
Medipix2
LVDS
DAC biasPower filter
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)
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
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
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
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
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
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