Floating point Square-root IP produces incorrect results in LogiCORE v5.0!!!

[javad2040]

Hello guys,

I design Spartan6 FGPA board that have ADC and SDRAM and i want to capture data and take RMS with LogiCORE v5.0 IPs. I use one Multiplier , Adder, Fixed-to Float and Square-root Floating-point IP.

In first step, the Latency and cycle/operation parameters of Square-root is set to 1 that the result produced correctly (I multiply the 14 and 15 decimal values by Multiplier IP and add it with 15, the produced value send to Fixed-to_Float IP and the result of it that is double-precision Floating-Point send to Square-root IP and the 15 decimal value produced that it is correct).

for next step, i increase the Latency and cycle/operation values that the result is correct, but when the Latency and cycle/operation is sets to 57 and 51 respectively, the result is incorrect.(blew figure)

the square-root of 225 value in floating-point system is 402E00 Hex but in blew figure the result is 402000 HEX that isn't correct.

Hint 1: In all steps the handshake signals of Fixed-to-float and Square-root unit(operation_nd, operation_rfd and opreation_rdy) not works but result produced.

Hint 2: I use LogiCORE v6.0 that IPs is AXI-based. the result produced correctly and handshake signals works fine.

Question 1 : In this project, the resource consumption is important, which IP is better for my project : LogiCore v5.0(without AXI) or LogiCore v5.0(AXI-based) ? 

Question 2 : How i can solve the problems that LogiCORE v5.0(without AXI) IPs work correctly? 

best regards