Pandora dev unit unboxed
[skeezix] has got his hands on one of the first Pandora dev kits to make it out the door and took a few photos. This is 1 of the 20 MK2 devboards that were produced. Although, not final it certainly is close to the version they’ll be shipping. Pandora is a Linux based portable game console. The main chip in the clamshell device is a TI OMAP3530. It has OpenGL hardware acceleration and an 800×480 touchscreen. A QWERTY keyboard is included along with analog and digital game controls. WiFi, bluetooth, USB host, TV-out, and dual SDHC card slots round out the package. The team has already presold 4000 devices.
Xbox 360 Jasper motherboards
The Xbox 360 has a brand new motherboard. Dubbed the Jasper, it presumably has a new 65nm process GPU. The new box has a 150W power supply instead of the former’s 175W brick. They’ve changed the plug design to prevent usage with old consoles. The most notable change is the onboard flash memory upgrade. Earlier consoles only had 16MB; new ones have 256MB. The majority of this storage will be used for the new dashboard, the NXE. The remaining space can be used for game saves. With the new storage, Arcade units are no longer including memory cards. You can see more images of the boards on Xbox-Scene.
Composite video through cat5
[mixadj] needed to run some video cable from one part of his house to another. He was lacking the proper amount of video cable, but had a bunch of cat5 laying around. so he built a converter to run his composite signal through the cat5. He states that he wouldn’t run it more than 70 feet without amplifying the audio somehow. Aside from that, the performance is supposedly decent. This just adds to the multitude of other uses for that Ethernet cable. We’ve seen voice, data, composite video, VGA, and power. What else have you seen run over cat5?
Make your own holiday lights
No matter what holiday you choose to acknowledge, you probably enjoy the thought of getting to put lights up everywhere. We know we do. Here are some instructions on how to make your own string of color changing lights. Sure, you can probably just buy a string of color changing lights for cheaper, but then you couldn’t arrange them however you want on the line, and you also wouldn’t get the satisfaction of doing it yourself.
96 LED POV
We pretty much don’t know anything about this POV device other than it uses 96 LEDs. We’ve seen POVs with more LEDs, but usually they aren’t packed in so tight. This thing looks almost capable of displaying low res movies. Wouldn’t this thing be cool, and probably dangerous, in a hat?
[via Hacked Gadgets]
Parts: 133MHz-16.2kHz programmable oscillator (DS1077)
The DS1077 is a 5volt, 133MHz to 16kHz programmable clock source. The internal frequency divider is configured over a simple I2C interface, and the chip requires no external parts. Not bad for under $2. We used the Bus Pirate to test this chip before using it in a project. Grab the datasheet (PDF) and follow along.
DS1077, $1.69 direct from Maxim + $10 shipping.
This chip isn’t available at any major distributors yet, but Maxim has them for under $2/each with a flat $10 shipping charge. This is an 8pin SOIC surface mount chip, so we made a small breakout board for testing.
Test circuit
Pin connections
| Bus Pirate | DS1077 (pin) |
| SCL | SCL (8) |
| SDA | SDA(7) |
| AUX | OUT1 (1) |
| +5volts | Vcc (3) |
| GND | GND, CTRL (4,5,6) |
We powered the DS1077 from the Bus Pirate’s 5volt power supply. Two resistors, R1 and R2, pull-up the I2C bus to 5volts when it’s not in use. Capacitor C1 is 0.01uF and C2 is 0.1uF, as recommended by the datasheet. Control pins provide some additional functions, but we bypassed them to ground during our test. Output1 is the primary clock signal pin.
Interfacing
| Address | Purpose |
| 0b10110000 | Default base address (0xB0) |
| 0xB0 | Write address |
| 0xB1 | Read address |
We put the Bus Pirate into I2C mode (M, options: I2C, 100kHz). The external pull-up resistors hold the bus at 5volts, so it’s important to leave the on-board 3.3volt pull-up resistors off (default).
I2C>{0b10110000} <– DS1077 write address
210 I2C START CONDITION
220 I2C WRITE: 0xB0 GOT ACK: YES <– got ACK
240 I2C STOP CONDITION
I2C>
First, we broadcast the DS1077’s address and see if it acknowledges. The address of the DS1077 is 1011, plus three programmable bits (000 by default), and the read (1) or write (0) bit. We got an ACK, so we know that the circuit is working and our connections are good.
| Address | Bytes | Register |
| 0×01 | 2 | 10 bit clock divider, n+2 (DIV) |
| 0×02 | 2 | Prescaler, CTRL pin functions. (MUX) |
| 0×0D | 1 | Address select, EEPROM write control. (BUS) |
| 0×3F | 0 | Save settings to EEPROM (E2) |
The DS1077 is controlled by writing values to the locations shown in the table.
I2C>{0xb0 0×0d 0b00001000} , <–write to BUS register
210 I2C START CONDITION
220 I2C WRITE: 0xB0 GOT ACK: YES <–DS1077 write address
220 I2C WRITE: 0×0D GOT ACK: YES <– BUS register
220 I2C WRITE: 0×08 GOT ACK: YES <– BUS register setting
240 I2C STOP CONDITION
I2C>
By default, the DS1077 saves all changes to the EEPROM. We don’t need this during testing, so we disable it by setting bit 3 (0b1000) of the BUS register (0×0d). The first four bits must be left as 0, the last three bits select the address to accommodate multiple DS1077s on the same I2C bus. See datasheet page 7.
I2C>{0xb0 0×02 0b00011000 0b00000000} <–set the 16bit MUX value
210 I2C START CONDITION
220 I2C WRITE: 0xB0 GOT ACK: YES <–DS1077 write address
220 I2C WRITE: 0×02 GOT ACK: YES <–MUX register
220 I2C WRITE: 0×18 GOT ACK: YES <–data byte 1
220 I2C WRITE: 0×00 GOT ACK: YES <–data byte 2
240 I2C STOP CONDITION
I2C>
The MUX register controls the prescalers, CTRL pin functions, and frequency divider. We disable the prescaler and CTRL pins, and enable the 10bit frequency divider. The MUX register is explained on page 5 of the datasheet.
Specific frequencies are generated by dividing the 133MHz reference frequency through the prescalers and a 10bit (1025 level) programmable divider. The clock is divided by the amount specified in the DIV register, plus two. When DIV=0, the output is 133MHz/2=66MHz.
This scheme gives the best frequency resolution in low ranges, and no steps between 133MHz and 66MHz.
I2C>{0xb0 1 0b11111111 0b11000000} <–DIV=1025
210 I2C START CONDITION
220 I2C WRITE: 0xB0 GOT ACK: YES <–DS1077 write address
220 I2C WRITE: 0×01 GOT ACK: YES <– DIV register
220 I2C WRITE: 0xFF GOT ACK: YES <– bits 9:2
220 I2C WRITE: 0xC0 GOT ACK: YES <– bits 1:0
240 I2C STOP CONDITION
I2C>f <–do a frequency count
9xx FREQ COUNT ON AUX: 16128Hz (16kHz) <– DS1077 frequency
I2C>
We set all the bits in the DIV register to 1 for maximum frequency division. ‘F’ measures the frequency on the AUX pin, which is connected to the DS1077 clock output. With DIV=1025, the frequency is about 16kHz.
I2C>{0xb0 1 0 0} <– DIV=0, 133MHz divide by 2
…
9xx FREQ COUNT ON AUX: 0Hz <–66MHz, too fast to count————-
I2C>{0xb0 1 0 0b10000000} <– DIV=2
…
9xx FREQ COUNT ON AUX: 3339696Hz (33MHz) <–133MHz/4————-
I2C>{0xb0 1 0b00000001 0b00000000} <–DIV=4
…
9xx FREQ COUNT ON AUX: 22192384Hz (22MHz) <–133MHz/6
We can play with the divider and generate a range of frequencies. The output is always equal to the reference frequency (133MHz) divided by DIV+2. The Bus Pirate’s input pin is only capable of measuring about 50MHz, so the highest speeds don’t register. A future version of the Bus Pirate should include a gigahertz prescaler for high frequency measurement.
I2C>{0xb0 0×3f} <–write E2 register
Finally, we can write the E2 register (0×3f) to save these setting in the EEPROM. The DS1077 will now return to these settings at power-on.
Conclusion
The DS1077 simplifies complex clock sources by moving a programmable oscillator and frequency divider into a single chip. It isn’t available from distributors, but you can buy it directly from Maxim. If you need better control of high frequencies, check out the DS1085 with 10kHz steps from 133MHz to 8kHz. The DS1085L is a 3.3volt, 66MHz version available at Digikey.
You received this email because you are subscribed to the real_time feed for http://hackaday.com/feed/. To change your subscription settings, please log into RSSFWD.
No comments:
Post a Comment