X68C75

This section gives examples of most widely used embedded systems architectures using the X68C75 and 68HC11 microcontroller. However, keep in mind that other microcontrollers are also supported by the X68C75 and/or other SLIC devices that Xicor manufactures.

Example 1
In this system, the X68C75 is the only parallel device residing on the multiplexed address and data bus. There may be other peripherals on the system board which are controlled by the ports on the X68C75. This configuration maps the EEM to a memory address in the range of E000-FFFFH. The SFRM can be mapped to any of the 64 x 1K pages within the memory space.

Example 2
Applications requiring more than 8K bytes of program memory space can be implemented using the basic system architecture depicted in example 1 along with an additional memory device such as the X28C256. Since this device requires non-multiplexed address/data buses,the X68C75 LAM feature is used to output the low order address byte. The SFRM can be mapped to any 64x1K page, but the X28C256 should be mapped to the low memory address space and out of the E2M address range (E000-FFFFH). This technique may also be used for other external byte wide memories such as SRAMs or EPROMs.

The X68C75 is a highly integrated peripheral for the 68HC11 family of microcontrollers. The X68C75 integrates 8K-bytes of 5V byte-alterable nonvolatile memory,2 bidirectional 8-bit ports, 16 general purpose registers,programmable internal address decoding and a multiplexed address and data bus.

The 5V byte-alterable nonvolatile memory of X68C75 can be used as program storage, data storage, or a combination of both. The memory array is separated into two 4K-byte sections which allows read accesses to one section while a write operation is taking place in the other section. The nonvolatile memory also features Software Data Protection to protect the contents during power transitions, and an advanced Block Protect register which allows individual blocks of the memory to be configured as read-only or read/write.