SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
Table 12-4129 describes the GPMC clocks.
Signal | I/O(1) | Description |
---|---|---|
GPMC_FCLK | I | Functional clock |
GPMC_ICLK | I | Interface clock |
CLK (GPMC_CLKOUT pin) | O | External clock provided to synchronous external memory devices and to DCC5 in the device. |
The GPMC output clock (CLK) is generated by the GPMC from the internal GPMC_FCLK clock. The source of the GPMC_FCLK is described in GPMC0 Clocks. The GPMC output clock is configured using the GPMC_CONFIG1_i[1-0] GPMCFCLKDIVIDER bit field (where i = 0 to 3), as shown in Table 12-4130.
Source Clock | GPMC_CONFIG1_i[1-0] GPMCFCLKDIVIDER | GPMC Output Clock Provided to External Memory Device |
---|---|---|
GPMC_FCLK | 00 | GPMC_FCLK |
01 | GPMC_FCLK/2 | |
10 | GPMC_FCLK/3 | |
11 | GPMC_FCLK/4 |
When using synchronous interface protocols, the GPMC output clock (CLK), toggles only during the read or write access cycle. In some applications, it may be desirable to have a continuous clock running at the GPMC interface clock frequency for clocking attached devices. This option is enabled by an optional clock path from the GPMC functional clock input (GPMC_FCLK) to the GPMC_FCLK_MUX pin. This output clock, to GPMC_FCLK_MUX pin, can be selected through the standard MUXMODE selection of the GPMC_FCLK_MUX pin PADCONFIG control register.
Note that when using such synchronous interface protocols with the continuous clock option, user should ensure that the GPMC outputs are timed to the same frequency (GPMC_CONFIG1_i[1-0] GPMCFCLKDIVIDER = 0).