The I/O pads located on the left and right sides are not hot-socketable because their PCI clamp is always enabled. The PCI clamp on the top side I/O pads is user selectable, and the bottom side I/O pads do not have the PCI clamp. This is the reason why only the top and bottom side I/O pads are hot-socketable. You must ensure that the PCI clamp is disabled on the top side IO pads if you want to make them hot-socketable.
The number of total hot-socketable I/O pads can be obtained from the pinout table (.csv) that you can download from our webpage (LatticeECP3 datasheet page), or generate from the Lattice Diamond tool. To generate the pinout table from Lattice Diamond, follow the steps listed below:
Once you get the pinout CSV (comma separate values) file, you can sort the I/O pads by the Pin/Ball column so that you can simply count the bonded out pins that have PTxxA/B and PBxxA/B entries.