The company said it will continue support for its current Z8 Encore! The devices are designed to meet the needs of designers working on consumer and. Microcontroller (MCU) Develop- because our kit then serves as your complete Z8 Encore!® additional cost allowing you to begin your design immedi- ately. What would be better than designing a softcore to learn more about VHDL ( VHSIC hardware I ended up choosing a modern Z relative: the Zilog Z8 Encore!.

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That way, your application code will start running following a reset signal. That is why I ended up writing two units: The opto-isolated USB smart cable is available as a stand-alone product, and is compatible with most Z8 Encore! With its lightweight Deslgning integrated development environment and free ANSI C compiler, it is an excellent project to learn and also teach about embedded systems.

Note that some instruction decoding can make use of several functions and procedures written specially for the FPz Note that I am not using bidirectional buses for any interconnects in this project. Learning Electronics Need to brush up on your electronics principles? Addresses 0x and 0x are dedicated to the configuration options; addresses 0x and 0x store the reset vector; and so on.

Another feature that the Z8 Encore!

Unidirectional buses are simpler to use, although they are less space efficient. After a lot of tests and some Googling, I figured out that it was possibly related to the asynchronous edges of the serial input signal. Thus, any program downloaded to it is lost when the FPGA is powered down. Everything started to work perfectly! To my surprise, while most of the time I could successfully send commands and receive the expected results, sometimes the design would simply freeze and stop responding.


These multi-part series may be rncore what you need! As I said before, eZ8 has a vectored interrupt controller with programmable priority.

The design makes use of a nested IF chain which generates a vector address upon detection of an interrupt event regarding an enabled interrupt. The result was absolutely weird.

Zilog Document Download

Instruction decoder design started by figuring out the relation among all the instructions and addressing modes. The program memory area is organized so that the first addresses are dedicated to special purposes. My OCD design implements almost all commands available on the real hardware, except for those related to data memory debug commands 0x0C and 0x0D ; the read runtime counter 0x3 ; and the read program memory CRC 0x0E.

Just ignore the warning and proceed with the debugging session. MC which eliminates the need for an external comparator. My design had worked microcontrooler in simulation. At first, I thought this section would not be so difficult because interrupts are no big deal, right?

Decoding an INC r1 instruction is simple: This was inwhen I had more contact with programmable logic and VHDL and my curiosity was peaked. While this would work for columns 0x2 to 0x9, we would need another approach for the first two columns.

Just keep in mind that the FPz8 has a volatile program memory. One last comment regarding interrupts: You can supply a hex file and use the MegaWizard Plug-in Manager to change the program memory initialization file. On-chip peripherals such as an optimized PWM module, a fast 2. The decoder stage uses this number to verify that the desired number of bytes for the instruction is already available in the queue.


Well, when I started to figure out how to do all the needed tasks saving context, vectoring, managing priorities, etc. The eZ8 core also includes a vectored interrupt controller with programmable priority and an on-chip debugger which communicates with the host computer using asynchronous serial communication.

One major feature of the eZ8 fhe model is the lack of a fixed accumulator. Another important detail is that all instructions within the same column and group are the same size in bytes, thus can be decoded in the same decoder section. This article is focused on learning how a microcontroller core is designed, and is intended for educational use only.

After thinking a bit and reading compiler output messages, I figured out that it was probably a timing issue. Free software upgrades are available. One thing I would like to highlight is care is needed when dealing with asynchronous signals inside FPGAs. It is responsible for detecting any pending interrupts and prepares the CPU accordingly.

Building Your Own Microcontroller

When the comparator is tied to the PWM module, safe shutdown is possible, even with the loss of the oscillator. The five register area buses comprise three for the file register area user RAMand another two dedicated to special function registers. That means the CPU can fetch a new instruction while another is reading or writing into data memory. You can set the desired communication speed as well;bps works very well for me.

The mini witu features along with the EP4CE6 device: