Conrad C-Control Pro Mega Series, Manual

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39 C-Control Pro Mega Series
© 2008 Conrad Electronic
74HC165.
SRAM
The application board holds an SRAM chip (K6X1008C2D) made by Samsung. By using this the
available SRAM memory is extended to 64kByte. Mentioned SRAM uses Ports A, C and partly
G for triggering. If the SRAM is not used then it can be de-activated by JP7 and then these
ports become available to the user.
To deactivate the SRAM the jumper JP7 has to be moved to the left side (orientation: serial
interface shows to the left), such that the left pins of JP7 are connected.
Even though the used RAM chip has a capacity of 128kb only 64kb can be used for reason
of the memory model.
I2C Interface
Through this interface serial data can be transmitted at high speed. To do this only two signal lines
are necessary. Data transmission takes place according to the I2C protocol. To effectively use this
interface special functions are provided (see Software Description I2C).
I2C SCL I2C Bus Clock Line PortD.0
I2C SDA I2C Bus Data Line PortD.1
Power Supply (POWER, 5 Volt, GND)
Power is provided to the application board by means of a 9V/ 250mA Mains Plug-in Power Supply.
Depending on additionally used components it may later become necessary to use a power supply
with higher power rating. A fixed voltage control generates an internally stabilized 5V supply voltage.
This voltage is provided to all circuit components on the application board. Due to the power reserve
of the Plug-In Power Supply this voltage can also be used to power external ICs.
Please observe the Maximum Drawable Current . Exceeding this current may lead to immediate
destruction! Because of the relativelly high current consumption of the application board in the
vicinity of 125mA it is not recommended for use in devices consistently battery operated. Please see
the note on short time breakdowns of the power supply (see
Reset Characteristics ).
If you turn the application board to a position where the interface connectors (USB and serial)
show to the upper side, the leftmost column on the breadboard is GND and the rightmost column is
VCC.
Serial Interfaces
The Micro Controller Atmega128 contains in its hardware two asynchronous serial interfaces
according to RS232 standards. The format (Data Bits, Parity Bit, Stop Bit) can be determined during
initialization of the interface. The application board contains a high value level conversion IC for both
interfaces to transform the digital bit streams to Non Return Zero Signals in accordance with the
RS232 standards (positive voltage for low bits, negative voltage for high bits). The level conversion IC
makes use of an improved protection against voltage transients. Voltage transients can in electro-