SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
Table 13-167 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 13-168.
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 GPMC functional clock input (GPMC_FCLK) to GPMC_FCLK_MUX. And output of this mux can be selected by CLKOUT_SEL bit field for GPMC_CONTROL Register present in MSS_CTRL. For more details, see MSS_CTRL chapter in GPMC Global Configuration.
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).