Mar 24
USBtoparallel
This device was built using AVRUSB firmware developed by extern Objective Development.
Meanwhile, a very similar Release 1.6 exists.
This Low-Speed device violates following USB specification rules:
* Detachable cable (must be captive for Low-Speed)
* Output drivers with 5 V (must be 3.3 V, but USB is 5 V tolerant)
* No differential data input (only one line D- is sampled)
* No data clock regenration while receiving (only at packet start)
* No error detection of input data (OUT direction), no time for CRC16
* Data transfer using BULK pipes (not specified for low-speed, but works on Windows – for Linux there is an “Alternate Setting” with INTERRUPT pipes instead)
However, new to this firmware, following rules are accepted:
* Suspend detection and lowered suspend current (below 500 µA)
[Via]
Mar 23
Do you think it’s very fussy to deal with the LED, especially when you have to change the broken LED Signboard all by yourself? Well, you should stop complaining and start repairing it, as time is precious…
First thing first, you have to open the signboard and check the problems. To be honest, when you’re looking on the signboard like the below figure, you must be shocked and doubt if you can ever get it fixed.
The truth is many parallel series chains of LEDs are the only reasonable way to design something like this. It’s reasonable to make chains of three each blue and white LEDs, as is given the respective voltage a great drops.
After that, it’s time to start with the power connection for the signboard. Normally, most of the plugs are designed to make good mechanical contact when it’s sunk completely into the jack. Sometimes, the springiness of the [...] [Via]
Uncategorized
No related posts.
Mar 23
* R1-R4 = 220R
Atmega 128 is like other AVR microcontrollers. They are ISP - is in-system programmable. Earlier I wrote an article about AVR ISP programmer where 74HC244 buffer is used. Using buffer is safer for your AVR.
But what if you need 128 atmega programmer without any parts, then you can connect your microcontroller directly to LPT port or use protection resistors (220R) just in case. of course circuit works without resistors, but you put your LPT port at risk.
Read the rest of this entry »
Mar 23
The Universal Serial Bus (USB) interface has become extremely popular, due to its simplicity for end user applications (Plug and Play without restart). For developers, however, USB implementation into end systems has been more complicated compared to e.g. RS232. In addition there is a need for device drivers as software support on the PC side. Because of this, RS232 based communication is still very popular among end systems manufacturers. This interface is well established and has good operating system support, but recently the physical RS232 port has been removed from the standard PC interface, giving ground to USB ports. Implementation of USB into external devices can be done in two ways:
1. By using a microcontroller with hardware implemented USB interface. It is necessary to know how USB works and write firmware into the microcontroller accordingly. Additionally, it is necessary to create a driver on the computer side, unless if the operating system includes standard USB classes. The main disadvantage is the lack of availability of this kind of microcontrollers and their high price compared to simple “RS232” microcontrollers.
Read the rest of this entry »
