From 10d14146ef84fbe4670454bc0996854a4066cfea Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Tue, 12 Sep 2017 13:40:06 -0700 Subject: [PATCH] chaoskey: Wait for input data to stabilize before using it The ADC data takes a while to start working after power on; wait for the range of input values to look reasonable before using the data. Signed-off-by: Keith Packard --- src/drivers/ao_trng_send.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/src/drivers/ao_trng_send.c b/src/drivers/ao_trng_send.c index b1227aaa..7cda053d 100644 --- a/src/drivers/ao_trng_send.c +++ b/src/drivers/ao_trng_send.c @@ -153,10 +153,20 @@ ao_trng_send(void) ao_crc_reset(); - ao_delay(TRNG_ENABLE_DELAY); - for (s = 0; s < AO_TRNG_START_WAIT; s++) { - if (ao_trng_get_cooked(buffer[0])) + int i; + uint16_t min, max; + uint16_t buf[AO_USB_IN_SIZE>>1]; + + ao_trng_get_raw(buf); + min = max = buf[0]; + for (i = 1; i < (AO_USB_IN_SIZE>>1); i++) { + uint16_t v = buf[i]; + if (v < min) min = v; + if (v > max) max = v; + } + /* Wait for at least 10 bits of range */ + if ((uint16_t) (max - min) >= 1024) break; ao_delay(AO_MS_TO_TICKS(10)); } -- 2.47.2