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zinger: do not trigger OCP on transients

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Ensure that the slow OCP (thermal/power protection) is not triggering
for power spikes below 20us, by sampling 4 times (with a 5us sampling
period).

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=chrome-os-partner:28331
TEST=connect Zinger to Firefly+electronic load, test with various
current pulse widths and amplitudes.

Change-Id: Ic8150dbbf191c002bba9e8d3f70beb47af4577b9
Reviewed-on: https://chromium-review.googlesource.com/204588
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Tested-by: Alec Berg <alecaberg@chromium.org>
Commit-Queue: Alec Berg <alecaberg@chromium.org>
This commit is contained in:
Vincent Palatin
2014-06-18 18:08:04 -07:00
committed by chrome-internal-fetch
parent 1faa6ee202
commit 47e74b8ca8
1 changed files with 22 additions and 5 deletions
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27
board/zinger/usb_pd_policy.c
View File

@@ -205,18 +205,35 @@ int pd_board_checks(void)
/* re-enable fast OCP */
adc_enable_watchdog(ADC_CH_A_SENSE, MAX_CURRENT_FAST, 0);
if ((fault == FAULT_FAST_OCP) || (vbus_amp > MAX_CURRENT)) {
debug_printf("OverCurrent : %d mA\n",
vbus_amp * VDDA_MV / CURR_GAIN * 1000 / R_SENSE / ADC_SCALE);
if (fault == FAULT_FAST_OCP) {
debug_printf("Fast OverCurrent\n");
fault = FAULT_OCP;
/* reset over-current after 1 second */
fault_deadline.val = get_time().val + OCP_TIMEOUT;
return EC_ERROR_INVAL;
}
if (vbus_amp > MAX_CURRENT) {
/* 3 more samples to check whether this is just a transient */
int count;
for (count = 0; count < 3; count++)
if (adc_read_channel(ADC_CH_A_SENSE) < MAX_CURRENT)
break;
/* trigger the slow OCP iff all 4 samples are above the max */
if (count == 3) {
debug_printf("OverCurrent : %d mA\n",
vbus_amp * VDDA_MV / CURR_GAIN * 1000
/ R_SENSE / ADC_SCALE);
fault = FAULT_OCP;
/* reset over-current after 1 second */
fault_deadline.val = get_time().val + OCP_TIMEOUT;
return EC_ERROR_INVAL;
}
}
if ((output_is_enabled() && (vbus_volt > voltages[volt_idx].ovp)) ||
(fault && (vbus_volt > voltages[volt_idx].ovp_rec))) {
debug_printf("OverVoltage : %d mV\n",
vbus_volt * VDDA_MV * VOLT_DIV / ADC_SCALE);
if (!fault)
debug_printf("OverVoltage : %d mV\n",
vbus_volt * VDDA_MV * VOLT_DIV / ADC_SCALE);
/* TODO(crosbug.com/p/28331) discharge */
fault = FAULT_OVP;
/* no timeout */