Serial Communication Protocol Conversion and Circular Buffer Implementation in FPGA using Verilog

Raja Ramanna Centre for Advanced Technology (RRCAT) has two synchrotron radiation sources, Indus-1 and Indus-2. Microtron is the common injector to both the machines. A new, FPGA based, control system architecture is planned in which it supervises and monitors different subsystems present for the operation of Microtron with the help of Equipment Control Modules (ECMs). At present some subsystems communicate with operator console directly over RS232 interface such as the ‘Tesla Meter’ and the ‘Temperature Scanner’. For modularity, those subsystems must be brought over RS485 interface and with unified pre-defined custom protocol for communication. In this paper monitoring of the Tesla Meter is proposed. An ECM communicates with Tesla Meter over RS32 interface and with an operator console over RS485 interface. Digital logic is designed in Verilog HDL and implemented in FPGA for RS232 and RS485 communication controllers, respectively. A protocol conversion unit between Tesla Meter and ECM is also implemented. For more feature, there is a need to capture data and store it for offline data analysis. Therefore, a circular buffer is also designed and simulated to review the history data from the ECM. The work has been completed using ModelSim XE and Xilinx ISE 8.2i softwares.