MEMCONF provides power control for RAM blocks.
Each RAM block can independently power up or power down in System ON and System OFF mode. RAM blocks can contain multiple RAM sections. For more information about System ON and System OFF modes, see Power and clock management. For an overview of available RAM blocks and RAM sections, see Memory.
- RAM sections to be retained during System OFF mode
- RAM sections to be retained and accessible during System ON mode
In System OFF mode, a RAM section is retained by configuring the corresponding MEM[i] field of the RET register.
In System ON mode, retention and accessibility for a RAM section is configured in the corresponding MEM[i] field of register POWER[n].CONTROL (n=0..1).
A complete list of blocks (RET.MEM[i], RET2.MEM[i], and CONTROL.MEM[i]) are found in the following table.
| Block number (index i in MEMCONF.POWER) | RAM section | RET reset value | CONTROL reset value |
|---|---|---|---|
| 0 | RAM00 section 0 | 1 | 1 |
| 1 | RAM00 section 1 | 1 | 1 |
| 2 | RAM00 section 2 | 1 | 1 |
| 3 | RAM00 section 3 | 1 | 1 |
| 4 | RAM00 section 4 | 1 | 1 |
| 5 | RAM00 section 5 | 1 | 1 |
| 6 | RAM00 section 6 | 1 | 1 |
| 7 | RAM00 section 7 | 1 | 1 |
| 8 | RAM01 section 0 | 1 | 1 |
| 9 | RAM01 section 1 | 1 | 1 |
| 10 | RAM01 section 2 | 1 | 1 |
| 11 | RAM01 section 3 | 1 | 1 |
| 12 | RAM01 section 4 | 1 | 1 |
| 13 | RAM01 section 5 | 1 | 1 |
| 14 | RAM01 section 6 | 1 | 1 |
| 15 | RAM01 section 7 | 1 | 1 |
| 33 | ICACHE tag + data 1:0 | 0 | 1 |
| 34 | USBHS | 0 | 1 |
A list of features that are retained using MEMCONF are found in the following table.
| Block number (index i in MEMCONF.POWER) | Feature | RET reset value | Description |
|---|---|---|---|
| 32 | Restore VPR context at VPR reset | 0 | Enables VPR context restore from RAM after VPR reset, where the VPR reset maybe caused by a wakeup from hibernate. 1 |
The following table summarizes the behavior of the CONTROL and RET fields when a power domain is powered on or off. The RAM section can be used to read and write data when it is powered. The RAM section is retained during System OFF.
| Configuration | RAM section status | |||
|---|---|---|---|---|
| Power mode | CONTROL | RET | Powered | Retained |
| System OFF | Any value | Off | No | No |
| System OFF | Off | On | No | No |
| System OFF | On | On | No | Yes |
| System ON IDLE | Off | Any value | No | No |
| System ON IDLE | On | Any value | No | Yes |
| System ON RUN | Any value | Any value | Yes | Yes |
The advantage of not retaining RAM content is reduced overall current consumption.
See chapter Memory for more information on RAM sections.