Retention(upf)

UPF provides set_retention and set_retention_control constructs to add retention strategy in the design.

Syntax :

set_retention retention_name
-domain domain_name
[-retention_power_net net_name
-retention_ground_net net_name]
[-elements list]

set_retention_control retention_name
-domain domain_name
-save_signal {{net_name }}
-restore_signal {{net_name }}
[-assert_r_mutex {{net_name }}]*
[-assert_s_mutex {{net_name }}]*
[-assert_rs_mutex {{net_name }}]*


A simulation model for retention cell :

reg save_q; // shadow register
always @( posedge save_1 )
begin // save process
save_q <= q;
end

always @( negedge restore_1 )
begin // restore process
q <= save_q;
end

Example :

set_retention ret3
–domain PDgreen
–retention_power_net Vbu ----> Back up vdd
–elements { u37 } ----> Name

set_retention_control ret3
–domain PDgreen
–save_signal s ----> SAVE
–restore_signal r ----> RESTORE