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[ion/device/drivers/external_flash] Clarify ChipSelectHighTime

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This commit is contained in:
Ruben Dashyan
2019-03-22 13:22:41 +01:00
parent 5babf98007
commit d34c5d3df9
1 changed files with 5 additions and 1 deletions
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6
ion/src/device/shared/drivers/external_flash.cpp
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@@ -91,8 +91,8 @@ public:
};
static constexpr QUADSPI::CCR::OperatingMode DefaultOperatingMode = QUADSPI::CCR::OperatingMode::Quad;
static constexpr int AHBClockFrequency = 192; // MHz
static constexpr int ClockFrequencyDivisor = 2;
static constexpr int ChipSelectHighTime = (ClockFrequencyDivisor == 1) ? 3 : (ClockFrequencyDivisor == 2) ? 2 : 1;
static void send_command_full(QUADSPI::CCR::FunctionalMode functionalMode, QUADSPI::CCR::OperatingMode operatingMode, Command c, uint8_t * address, uint32_t altBytes, size_t numberOfAltBytes, uint8_t dummyCycles, uint8_t * data, size_t dataLength);
@@ -238,6 +238,10 @@ static void initQSPI() {
// Configure controller for target device
class QUADSPI::DCR dcr(0);
dcr.setFSIZE(NumberOfAddressBitsInChip - 1);
/* According to the device's datasheet (see Sections 8.7 and 8.8), the CS
* signal should stay high (deselect the device) for t_SHSL = 30ns at least.
* */
constexpr int ChipSelectHighTime = (30 * AHBClockFrequency + ClockFrequencyDivisor * 1000 - 1) / (ClockFrequencyDivisor * 1000);
dcr.setCSHT(ChipSelectHighTime - 1);
dcr.setCKMODE(true);
QUADSPI.DCR()->set(dcr);