p2 of 8
26-Aug-10
USB-DAQ
HW147-5
www.hexwax.com
Basic Operation
USB-DAQ contains a FAT file system on which files can
be stored. When plugged into a Windows, Linux or Mac
PC, USB-DAQ looks like a flash drive and files can be
directly accessed without the need to install drivers or
software. The file can be stored in internal memory (8
kByte), external 25AA1024 memory (128 kByte), or SD
cards or chips up to 1 GByte. The PC can create, read,
write and delete files and subdirectories as required.
In addition to functioning as a flash drive, USB-DAQ has
a data acquisition / process control engine and a real
time clock that allow it to function autonomously when
not connected to the PC. A file named CONFIG.DAT in
the root directory controls the chip’s function when
operating in this mode. This file is created in a Microsoft
Excel application and includes instructions to execute on
startup, and when an interrupt or real-time-clock event
occurs. USB-DAQ can read and write to up to four files
in the root directory; it does not create them, delete
them, or change their length.
When a file in the root directory is modified by the PC,
USB-DAQ notes the modification date and time data in
the directory entry and use this information to set the
time on the real time clock.
Electrical Specifications
Table 2. Electrical Specifications
Operating voltage Vdd, 28-pin device
2.7V – 5.5V
Operating voltage Vdd, 20-pin device
1.8V – 5.5V
Typical/max supply current, Vdd = 5.0
10mA / 21mA
Typical/max Sleep current, Vdd = 5.0
0.1μA / 2μA
Operating Temperature
-40°C to +85°C
Refer to base MCU data sheets in the dev kit for further information
Device Pinout
Figure 2, Device Pinout
Table 3. 28-Pin Device Pinout
Pin
Name
Description
1
Media
Vpp
Media detect input
TEAclipper programming pin Vpp
2
RA0
General I/O pin
3
RA1
General I/O pin
4
RA2
General I/O pin
5
RA3
General I/O pin
6
RA4
Escape
General I/O pin
Escape input pin
7
RA5
General I/O pin
8, 19
Vss
Power ground reference
9
OSCA1
12MHz oscillator input
10
OSCA2
12MHz oscillator output
11
OSCB1
RC0
32768Hz oscillator input
General I/O pin (if no 32768Hz oscillator)
12
OSCB2
RC1
32768Hz oscillator output
General I/O pin (if no 32768Hz oscillator)
13
MISO-M
RC2
Data input from SPI memory
General I/O pin (if no external memory)
14
Vusb
USB supply filter
15
D-
USB data -
16
D+
USB data+
17
RC6
General I/O pin
18
RC7
General I/O pin
20
Vdd
Regulated supply input
21
RB0
General I/O pin
22
RB1
General I/O pin
23
RB2
General I/O pin
24
RB3
General I/O pin
25
SSn-M
RB4
Slave select output to SPI memory
General I/O pin (if no external memory)
26
USB-S
USB voltage sense
27
MOSI-M
RB6
PGC
Data output to SPI memory
General I/O pin (if no external memory)
TEAclipper programming pin PGC
28
SCK-M
RB7
PGD
Clock output to SPI memory
General I/O pin (if no external memory)
TEAclipper programming pin PGD
Table 4. 20-Pin Device Pinout
Pin
Name
Description
1
Vdd
Regulated supply input
2
OSCA1
12MHz oscillator input
3
OSCA2
12MHz oscillator output
4
RST#
Vpp
Device reset input (active low)
TEAclipper programming pin Vpp
5
RC5
General I/O pin
6
RC4
General I/O pin
7
RC3
General I/O pin
8
OSCB1
RC6
32768Hz oscillator input
General I/O pin (if no 32768Hz oscillator)
9
OSCB2
RC7
32768Hz oscillator output
General I/O pin (if no 32768Hz oscillator)
10
SSn-M
Slave select output to SPI memory
11
SCK-M
Clock output to SPI memory
12
MISO-M Data input from SPI memory
13
MOSI-M Data output to SPI memory
14
RC2
General I/O pin
15
USB-S
USB voltage sense
16
RC0
Escape
General I/O pin
Escape input pin
17
Vusb
USB supply filter
18
D-
PGC
USB data -
TEAclipper programming pin
19
D+
PGD
USB data+
TEAclipper programming pin
20
Vss
Power ground reference